Okay, if you admit that it's just what you want Batman to wear, that's cool. I myself would be very tempted to see Bale in a black/grey suit. But I care more about what makes sense for his character, especially when Nolan is going with a serious interpretation of the character that involves good rationale behind all the features of his costume.
This is not correct (hint: there was no reason for him not to paint the belt black, too. No reason this "no need to explain it" approach can't be applied to a grey bodysuit).
Bruce cares about aesthetics only to the degree that he wants to look as much like a creature of the night as possible, and he just chose a bat motif for psychological and practical reasons, not aesthetical ones.
This is not correct either: Batman is
not only concerned with looking like a "creature of the night." I don't want to repeat myself, so please read
this post.
His mindset is not concerned about mixing things up with some grey color because it's visually pleasing,
I don't recall ever saying anything about pleasing. I said he's aesthetically minded--the suit is designed to be seen. The symbol is on his chest to be seen, or it would not be there at all.
His bat motif is justified by practical reasons. The ears on his cowl contain antennaes, and his cape functions as a glider. What practical purpose does having grey in his suit serve? And remember, camouflage does not make sense, as I explained.
It doesn't need to serve a purpose, by the same token that having it all black serves no purpose either.
The bat symbol on the chest is something that a comicbook artist thought of when designing Batman's costume. But is it something that Batman himself would have thought of in designing his costume? I'm not so sure, and I don't think the symbol on his chest is that important at all. Nolan kept it, and I'm not saying he shouldn't have, just that it's necessity is debatable.
If you believe this statement, then there is no point in us discussing this any further, because I actually want Batman to look like Batman.
But let's just say that Batman does care about aesthetics to the degree of putting the symbol on his chest. There is still a difference between using it to stress the symbol he embodies, and designing a suit that is less dark than it can be.
Secret tip: it can't stress "the symbol he embodies" if it can't be seen.
Finally, what does it matter if Bruce Wayne wants the suit to be aesthetically pleasing or not? This is not something that has ever been granted consideration in any Batman comic, ever--or for most heroes, period. The suit must be good-looking not because Bruce wants it to or not, but because character designs are supposed to look good, period. If this means all-black to you, fine, but don't waste my time with this "it shouldn't be grey because Bruce doesn't care about made-up-rationalization-X" crap.