Fan service is another marketing tactic. Sometimes it's there for a reason, and sometimes no reason at all other than to give the excuse to draw an attractive man or woman.
In all my comics, I have had people find some of my characters "hot" and had comments like
"When will they kiss?"
"Its OK to be gay / lesbian when are they coming out?"
"More naked pls..."
Most number of fan boys and fan girls among my ocs... none other than Akala.

Then a tie between Lucia and Claudita


And for male characters? Eman had some...

And from back in geocities days... Arbyn...
Here's a better drawn version of him...

And let's be honest... attractive characters keep and attract readers. 