Let me tell you 'bout the birds and the bees
How hot and spicy a writer goes is strictly personal. If they stray from their comfort level, you're going to notice. I've never been a fan of purple prose - those flowery ridiculous descriptions for body parts and the intimate act itself. That said, sex shouldn't be crude either, nor should it be gratuitous.
When I first started writing, I wasn't exactly sure where my stories fell in the romance genre because of the sex. Since my earlier books contained some fairly descriptive acts, I thought I might be straddling the line between contemporary and erotic romance (or romantica).
Erotic romance can be, and often is, confused with erotica, but there's a big difference. Erotica is heavy on encounters, isn't dependent on a love story, doesn't require a happy ending, doesn't even require two committed individuals. Threesomes are a common theme. If you removed the sex, the entire story would collapse. Erotic romance, on the other hand, is very definitely a romance following two people on their journey to love and commitment, except it doesn't close the bedroom door in the reader's face and do a graceful fadeout.
Over the years however, I've noticed a change. With the growing popularity of e-readers, women are buying hotter books without the guilt and embarassment. That means the lines are blurring. Mainstream romances are trending sensual and include more descriptive scenes. Over time, I predict the subcategory of erotic romance (romantica) will disappear entirely, though I could be wrong.