It's definitely common. I'm in one campaign that uses it, and you see it suggested an awful lot.
Many people feel expertise bonuses are necessary to make the math work. Here's the deal: if you extrapolate a character's attack bonuses and a monster's defenses, incorporating expected magic items and so on, the attack bonuses increase slower than the defenses. Therefore, without looking at any other factors, the characters hit less often as they level.
At level 1, a typical melee character has +4 to hit from his stats, +0 from his level, and let's say a +3 proficiency bonus from his weapon. That's a +7 to hit, versus a typical AC of 15 for a level 1 monster.
At level 30, the same character has +8 to hit from his stats, +15 from his level, +3 proficiency bonus from his weapon, and the weapon is +6 as well. That's a +32 to hit, but the monster has an AC of 44.
However, the PCs also get more situational bonuses as they go up in level. With higher level powers, they're more able to tilt the scales back in their direction; they have more ways to get combat advantage, more ways to reduce a monster's defenses, and so on. Some people feel these advantages even out the playing field such that the advantages you get from the Expertise feats are not necessary.
I can say that at paragon tier, I've found my PCs to be more effective against monsters due to those factors, but that is just one person and I can't at all speak to epic tier. There are some interesting threads here and here.
However, no matter which side of the fence you fall on, I think it's a good idea to do one of two things: either give everyone the expertise feats for free (you want to give out Implement Expertise as well, I note) or remove them entirely. The thing is, they're good enough so that people will usually wind up taking them at some point. If you think you need them, you'll take them immediately; if you don't think you need them, they're still worth taking if you want to make your character even more accurate.
Finally, it's worth noting my two sneaky little secrets about 4e. First, optimization doesn't matter. The game plays just fine if you have a 16 in your primary stat. I play a halfling barbarian, I spent the points to get an 18 Strength, and if you listen to the optimizers I'd have made a mistake and shorted myself elsewhere. But he's a blast.
Second, player skill matters at least as much if not more than optimized characters. If you show me a character with one of the expertise feats who's played by someone who doesn't get the importance of working with his group, and a character without any expertise feats who's played by someone who knows how to stay out of the way of his friend's area spells? I'll play with the latter and we'll have an easier time with the combats.
Best Answer
No.
Being able to pretend you are someone else does not make you someone else, nor does it grant you any of the talents or expertise it would take a real version of that persona a lifetime to accrue.
An actor can pretend to be a lawyer. Even if they fake their credentials and make it into court, it doesn't mean they will actually be able to prosecute a case with any talent.
A telemarketing scammer can pretend to be a bank agent. They might be able to convince you of that over the phone, but it doesn't mean they actually have access to a bank vault.
A charlatan can pretend to be a noble. They may have documentation and a persona they can use to fake their way into a party or exclusive audience, but they aren't actually a noble, so they don't necessarily have sufficient money, relationships with specific real people, and charisma needed to maintain the ruse for long, nor are all nobles automatically prestigious.
Mechanically, 1) you only gain a feature if a rule says you do and 2) if the Charlatan were intended to be able to take on another background's features then the rules would say so.