It is common to tell the story in novels in the past tense. When a story is narrated in the past tense, the past tense prose is equivalent to our present tense, as we follow the unfolding story.
NOTE: In my previous revision, I tried to simplify the reason of the use of the past tense to "to depicts events in the story as something happened before the time the author wrote the novel". But that is inaccurate. For example, a futuristic setting where people could travel faster than light is commonly told in the past tense too. (Credits go to F.E. for pointing this out to me in our chat room.) It's probably the best to think of the use of the past tense in novels as a literature device. Also note that there are several narrative styles. Narrating events in the past tense is the most common in novels.
It might be possible to write a story only in the simple past tense, but that will make the sequence of the story very sequential, each of the sentences refers to a specific event in the story, one happened after another, on and on and on. Isn't that kind of boring?
Naturally, the author needs a way to describe events that happened before the moment happening in the story. How can they do that? To say things happened in the past before the past, as you already know, we use "the past perfect".
A Tense Shifting Experiment
To sum it up, in novels, we usually narrate in the past tense. The simple past tense is used for the usual present tense. And the past perfect is used for the usual present perfect and simple past.
To make things more clear, let's try a little experiment together. Let's see what it will be like if we write the same thing in the present tense.
Original:
When he had walked me to my door, he had kissed me. Like before, it had felt good, and the closeness had been nice. His taste was warm, and the gentle touches of his tongue against mine had been exciting. I had been happy to stand outside and kiss him for hours. But Linc had ended the kiss and then let out a deep breath before kissing me on the forehead and saying goodnight.
Let's shift the whole narrative to the present tense:
When he walked me to my door, he kissed me. Like before, it felt good, and the closeness was nice. His taste is warm, and the gentle touches of his tongue against mine was exciting. I would be happy to stand outside and kiss him for hours. But Linc ended the kiss and then let out a deep breath before kissing me on the forehead and saying goodnight.
Since the past perfect is used for the usual present perfect and simple past, it's up to the reader to interpret which one makes more sense to them. This is one possible interpretation.
One thing is clear. The only "present" in the narrative is this part, "His taste was warm". The rest happened before this "present". Why? Because the past perfect forces that. So there's nothing wrong with the past perfects. In fact, I believe that they're required. (Though, as you seem to know, you don't have to use the past perfect unless you really have to).
What appears to be the author's intention is that the narrator (the one who put her memory into words for us) was thinking back to a kiss she had received earlier from Linc. So, that kiss becomes the "now" of her thought, as indicated by "was", in the narrative. And it seems to be the author's choice to use a lot of past perfects to narrate her reminiscence.
NOTE: In my previous revision, I shifted "I had been happy to ..." to "I was happy ...". This is less than idea, for the writer seems to intend that "I had been happy to ..." to actually mean "I would have been happy to ...". (This is probably to give us a hint about her personality.) So a better shifted-to-present version would be "I would be ...", which is equivalent to "I would have been ..." as it should have been in the narrative. With all the pieces falling into place, I decided to revise the shifting of "... against mine had been exciting." to "... was exciting.", too.
Now, let's get back to your question: whether your rewriting make sense or not?
As you can see now, if you replaced some past perfects with a simple past, it could change the order of what happened in the story.
Let's see what would happen if we applied your changes to the shifted-to-present version:
When he walked me to my door, he kisses me. Like before, it feels good, and the closeness was nice. His taste is warm, and the gentle touches of his tongue against mine was exciting. I would be happy to stand outside and kiss him for hours. But Linc ended the kiss and then let out a deep breath before kissing me on the forehead and saying goodnight.
Another issue is now obvious. "When he walked me to my door, he kisses me," is ungrammatical. (And so is "When he had walked me to my door, he kissed me.") We usually use when to state things that happen at the same time. Though when to after can fix that, but your story will be a different one. It also seems to make less sense than the original, "Linc ended the kiss" after "he kisses me". Isn't that strange?
Have done --- Have done is a present perfect tense, generally it is used when the action is completed recently/just now.
Had done-- Had done is a past perfect tense, generally refers to something which happened earlier in the past, before another action also occured in the past.
For Example:
We have done the work -- Here the action completed recently/just now.
My friend offered me an apple in classroom yesterday, but I wasn't hungry because I had just eaten lunch -- Here the action happened earlier("yesterday"), and another action ("I had just eaten lunch") also occured in the past.
Best Answer
The difference is in how the speaker (writer) is choosing to structure the temporal relationships. In many contexts, there is more than one possible choice; sometimes some of the choices are ruled out by objective circumstances, or by other words the speaker is choosing to use.
In this case, the choice of the present perfect (has introduced) would signify that the writer is choosing to convey some present relevance of the introduction. This is unlikely, because Kant died long ago, and would only be appropriate if the writer were conveying that Kant's action was part of a development that is still continuing.
The choice of the past perfect (had introduced) would indicate that the writer was focussing on some particular time in the past, but later than Kant's introduction. It would fit if the writer had already established that they were talking about some such time - perhaps the time of some subsequent development. Alternatively, the use of the past perfect could establish some later temporal focus, which the writer then went on to talk about further.
The simple past (introduced) is neutral, and doesn't have any such implications.
So in isolation, there is no reason to use the past perfect in that passage; but it could fit if it were preceded or followed by material set at some later time.