I think I look at it the other way around. I don't really buy that they're that deeply in love with each other in Season 3, and it seems less so in each of their later meetings. As such, most of those meetings leave me cold (at least), and the whole "Angel's my forever love and I'll never love anyone as much as him" thing really just irritates me. (For one thing, it's not romantic so much as astoundingly depressing.) The fact that Spike's my favorite character just helps seal my hatred for that scene in Chosen.

I believe they were in love in Season 2, to be certain, and that they thought of themselves as in love after that, but I don't think the intensity of feeling was actually there. I can see them *wanting* to reclaim that; for Buffy, it was when she was innocent and relatively happy, and for Angel, it's the one truly happy time in his last century-plus. So there's definitely warm feelings from nostalgia there. I can also see that they'll always still love each other on some level for the same reasons, plus, as you said, the first love aspect for Buffy. But I agree with you about a relationship being a bad idea (for more reasons than theirs), and then some, and I just find I can't buy the whole Buffy/Angel madly-and-forever-in-love vibe that the writers were so keen to sell.