I'd just like to get most of the stock arguments out of the way;
- Nobody is asking for spandex. Fabric-based is not the same as spandex. The comic costume is not spandex.
- A full black costume is actually worse at urban camouflage than a black and grey costume, or even a blue and grey costume (which military studies have confirmed is the most effective)
- There are several fan-made manipulations or actual constructed costumes that prove the comic design does not look silly.
- Molded rubber is not a realistic option, because the actors who actually had to wear them complained about a lack of mobility and overheating.
- Nobody complained that Catwoman isn't wearing armour in TDKR even though she is just as vulnerable as Batman is. You may say she has the advantage of stealth, well so does Batman.
- Realism is redundant when you still have the bat-ears and the cape, which are by far the least realistic aspects of the costume.
- Durable fabric-based materials exist.
- Audiences embrace 'silly' looking costumes as long as the movie is good. See Spider-Man, The Avengers.
- Posting pictures of Adam West proves the comic costume looks silly as much as posting pictures of George Clooney proves rubber armour looks silly.
Did I get them all?