Thanks for the thoughtful post.
We obviously don't know what Bioware are going to do, but it's probably fair to say they've learnt from some of the negative reaction to Anders - David Gaider, who was in charge of DA2's writing, said he probably wouldn't make that happen again if he had the chance to re-write it.
I can't speak for every fan of s/s romances - I'm sure some would insist that removing the option for a squadmate to hit on you is tantamount to giving in to complaints - but I'm firmly of the opinion that it's better not to annoy or frustrate people, and that it's still certainly possible to have good s/s romances without having them start it.
What do
do know, though, is that all romances in ME3 will be reactive and responsive to what the player does, not the other way around. Here's how Casey Hudson put it:

'Reactive to how you interact with them in-game' seems, to me, to mean that the player has to initiate everything. This is fine.
Frankly, I think Bioware were a bit dismayed by some of the response to Anders in DA2. It was certainly more visceral and louder than what people said about Zevran.
I'm not excusing those people - some of it was people complaining unreasonably and not recognising their own privilege - but I understand that Bioware has to juggle things very carefully. I suspect they're also being risk averse and cautious about s/s in ME3; the very positive response it's got from many people has been met by some very stupid criticism from others.
Long story short: I don't think you'll have anything to worry about. The romances will most likely be player-initiated, and it'll be obvious which lines lead to romancing. Mass Effect games have never given any negative consequences for rejecting romances, and I doubt they're going to start now. Bioware have an interest in making sure the s/s romances can be accessed by people who want them, and avoided by those who don't.