final-fantasy-15
FFXV has two types of combat, toggleable in the options:
There is an entire skill-tree labeled "wait mode". Is there any point in upgrading this tree if you're playing in Active Mode?
If you get the Analyze skill (6 AP, Ignis ability) on the Ascension Grid, you will automatically scan most enemies at the start of battle to see the HP and resistances (essentially Libra) of the enemy that you are locked on to.
No, not really
There are chapters that you do not have access to the means of returning. You always come out of those chapters eventually and have one or all of your travel tools back at your beck and call. In general, there is no point where you cant ever go back and finish things you have missed.
It is worth mentioning there is a 3rd continent near the end of the game you access for the main story line. Once you have entered into the final chapter of that continent, Chapter 13, and finished it, there is no way to return to that continent.
Best Answer
Wait Mode skill tree appeals to a Tactician whereas Active Mode appeals to a Strategist and the benefit of spending AP in WAIT MODE is great should you find more comfort in a tactical role.
The AP in wait mode is designed to give players the same scope of information afforded in Active Mode, standing still.
For example, on PS4 Libra is activated with R1 (RB in XBOX), but you have to select the target and you typically only have a brief moment you can check Libra during combat. In WAIT MODE, you can be more precise in your actions because you have time to plan while you do not move.
As long as you don't plan on playing in Wait Mode, you're fine without using AP in the skills. If you do plan on it at some point however, Wait Mode is weakened unless you use the AP. Fortunately, the AP required is minimal compared to other skill trees.