Most player concerns fall under a small variety of categories which result in them not being answered directly by a Rioter;
A: Have already been answered elsewhere.
B: Aren't legitimate. (like "X is too weak" when they just want their main buffed)
C: Can't be answered because nothing is set in stone
D: Can't be answered because there is a reveal date
E: The Rioter reading simply doesn't know for certain
F: The post hasn't been read (players outnumber Rioters by far)
There are certainly more, but the short of it is that Riot can't shouldn't wouldn't and won't sit around wasting their time answering players very often. The only games that get that kind of attention are the Indie games in early development and a small player base which doesn't have that many questions. LoL is literally the exact opposite of that.
If players researched their questions more often, there would be a lot less garbage posts because they'd be able to get the answer themselves, and maybe Riot could then efficiently answer legitimate concerns.