I agree with the general opinions on this topic, and with this:
Personally, I don't see why simulated romance and sex can't be a perfectly valid substitute for the "real thing". Certainly not for everybody, but I certainly don't agree that deliberately pursuing the single lifestyle IRL (and getting whatever "kicks" you need through such means as ERP) is intrinsically and universally bad or unhealthy.
It can also be used as a "safe" way to act out certain fantasies ones own RL partner might not be compatible with.
Even if its sole reason why characters interact, OOC or IC, it can be good.
IC because IRL, it happens as well.
OOC because sometimes you'll have no suitable characters (either because the players don't want it, or it would affect their RP/interaction in an undesired way) around in your regular circle to ERP with, but are not interested in/have the time for developing and maintaining another intensive relationship. It could be that a player is a

ERP-er but not a good RP-er in general

.
A sexual relationship can give birth to interesting plot lines or can also pump some new life in a RP relationship between characters that have interacted with eachother for a long time. Sometimes (if not most times) sex will have consequences: pregnancy, jealousy and new enemies, subtle or not so subtle changes in how characters interact (good or bad), unexpected alliances, an FC not responding to a CTA, waking up to find your vault cracked, being blackmailed, and falling in love (sometimes with a (sleeper) spy that seduces you). But of course you don't have to ERP to enjoy those benefits.
During my time in EVE, I've had only 2 ERP sessions so far, but it looks like that will change soon.
The first, about 8 months ago, was a kick-off point to a plot line that entertained quite some time, and I'm not even completely sure if I've heard the last of it (no, she's not pregnant).
The second took place early this week, and IC it had almost the same positive effect as OOC, namely to serve as a welcome break from a considerable period of drama-doomgloom-drama-sad-drama. Sometimes its the easiest way to give your character a break, and/or have an excuse to write something else than "/me bursts into tears", "I'll kill you!" or "I'm so happy!" for the umpteenth time that week.
(Multiple punsintended)