For you, that was the problem.
I'm pretty certain that a non-insignificant amount of people were angry just because a dude dared to hit on their dude. Liara was also disliked by some because of how she threw herself in the PC's arms, and the blow was softened by her being the requisite alien space babe.
I'm not sure people are ever going to take well that NPCs have the initiative regarding romances. At best they woud be Isabelas who makes tons of flirtatious comments but still wait for the player to give their go before things get serious.
People say that all the time as though they have access to some statistics and polls that were never actually done.
Zevran flirts with the PC regardless of gender, no-one was up in arms over that. Izzy ditto, still nothing. In DAI all the LIs are basically wall flowers who do nothing until you explicitly say something right in their face, twice.
I'd be willing to bet only a small minority had a problem with the M/M auto-flirt, instead most had the problem that (surprise) most people have pointed out: You have no middle-ground 'thanks, but no thanks.' Its either nice and start a romance, or mean and he gets all grumps.
Given the (apparent) setting of MEA populating a whole new sector and building human/Milky Way society here in Andromeda I'd love for at least some of the procreative gender appropriate (straight) romances to initiate flirting. I wouldn't mind if others did it, and as long as some potential romances initiated I'd be happy regardless of who they are.
The one thing we've never seen in a Bioware romance is one that doesn't work (Solas gets close, isn;t quite there). Have an NPC start the romance, have it progress, have unavoidable conflicts between LI and AndromaShep and have them break up. It seems like every relationship in Bioware games ends happily (JE every romance was happy fun times. ME is a bit more difficult to summarize with the whole 3 games thing, but apart from Thane and Jacob it is possible to be happy in all romances, and Jacob sucked anyway I could barely stand him long before ME3. DAO all have the happy route, including Morrigan since you can elope through the Eluvian, DA2 all can end well, DAI all can end well, even Solas still loves Lavellan, he haunts her dreams). I'd love to see a relationship that never has a chance of succeeding without anyone becoming enemies. Or an LI who is really just interested in a one-night-stand and doesn't reciprocate beyond that. Give us new stuff.