Why? to make yourself feel better for choosing the more complex option, like a reward or something? Personal preference of playstyle shouldn't mean "I'm mechanically better than you too." It just means "I like different things than you." In fact, the goal was to have both simpler and complex PCs at the same table with minimal difference in overall mechanical effectiveness. That was one of the worst problems with 3e, the system mastery disparity. If you choose the more complex option, that should be because that's what you prefer. It shouldn't be because you want to be better than the other players like it's some sort of competition.
No, not at all. When I say better, I mean in the nature of about 10-20% better, on average. I'm sure you don't think the disparity between 10 DPR and 12 DPR is so great that people who want to play simple characters won't be competitive.
And yes, I do think players who embrace mechanical challenges should receive a small bonus if they leverage those effectively. That's been the wizard shtick since Basic, after all. The balance point is that if the more mechanical complex character is played poorly, their DPR and effectiveness will suffer accordingly, more so than the mechanically simple character. It should look something like:
Battlemaster (played well) - 12 DPR
Champion (baseline, as they have no real DPR decision points) - 10 DPR
Battlemaster (played poorly) - 8 DPR.
Note, also, by "played well" I mean tactical decisions at the table, not build decisions. The problem with 3e was how much of your character's effectiveness was tied to decisions you didn't make in play, but at the time of character build.
There's also the issue of psychology. Players who gravitate towards mechanical complexity are, most of the time, also going to be players who are more aware of mechanical effectiveness, and are more than likely to gravitate towards playing more "effective" classes. I would be bummed if all the strongest options for characters were characters with purely passive abilities that required little to no decision making, because my desires for both complexity and effectiveness would be hindered.
Likewise, player types who gravitate towards the simpler options are also the type who care the least about measuring effectiveness. How many people on this forum make statements like "I don't care about my DPR, I just want to play the character I envision?" If they don't care about DPR, than why would more complex characters being slightly stronger than simpler ones matter to those players even one iota? They're going to choose the option that fits their concept and is easier to play.