I think my problem was that they tried to make Johnny devil-may-care in all the wrong ways, because yes, he is a risk-taking, jack-the-lad but he's not a huge flirt, and the Evans Storm was. Personally, with the usual YMMV, Quicksilver in Age of Ultron is a lot closer to how I imagine Johnny Storm.

I think it's part of this really odd thing where Hollywood has to make any attractive, unattached male a horn-dog because they think it appeals when it appeals to no-one (see also Reboot Kirk).