I do agree with the OP here.
I am quite shy and really don't like flirting in real life, but I am a bit of a hopeless romantic nonetheless. Unfortunately, this is one aspect of my personality which is also present when I game, despite my attempts to roleplay.
In DAO I must have accidentally encouraged Alistair, but I believed he was making the first move when he offered me the rose. In DA2 I liked that Anders and Isabela showed an interest from the outset. In DAI, everything was down to the PC which, while okay with me, wasn't really my preference.
So while I certainly don't want all the LIs to try and initiate a romance, I think that if the PC is making the right choices and treating the LI well, and if it suits the LI's character, having them show an interest first could add to the romance variety.
Obviously not everyone likes this approach, and some people would be vehemently against it, so I could understand if Bioware decided not to implement it again.
Edit: Funny story, just to illustrate my point:
The first time I played DA2, I took a liking to Fenris and wanted to romance him - but I never picked any of the flirt options, because I didn't want to make the first move! So, come endgame, I actually had no LI at all. I had to restart and made sure to hit a couple of flirt options.