Well it's always a damned if you do, damned if you don't type situation as a developer. Have a large cast and some people will complain it's too big. Have a small cast and some people will complain it's too small. I personally think LRH's cast has probably tipped a bit too far past the sweet spot, but it is what it is.
It goes for almost anything, in most case someone won't be happy with the decision you make as a dev. Sure, some of the may be doubtful or could even be wrong/bad, but it is what it is and the only way I say is to be upright about them and own them.
Don't know anyone who would make wrong/bad decision if he would have know it at the time he had make them. The rest everyone make some small or bigger mistake, it is what makes us us and in the best case we learn from them and grown up.
For this game, as for any others, it is, what it is. So either enjoy it for what it is or go search for another one that is more for your taste. I personally try to not interfere in the devs plan (that much). If I give some ideas, that could be used in the game, if they will be used, then I'm happy and if not, then I'm happy too.
Although I agree, that the cast is very big and as a result, we get little screen time per LI (that is purely mathematics nothing more). As other also stated the cast is unique and I haven't encountered a character that I would put under the label filler or is just here for diversity to fill the quote and please the players.