IMHO that episode was emblematic of everything that's gone wrong with the original L&O over the past few years.
The business of Serena being a lesbian was NEVER alluded to in her whole run as Jack's sidekick. I think it was meant as some sort of "gotcha" with absolutely no build-up beforehand.
And -
Let's talk real world here. Manhattan is one of the most sophisticated jurisdictions under the sun. Attorneys in the public sector are unionized. The District Attorney could no more fire an assistant ADA for something as meaningless as having an advocacy orientation rather than a "DA" orientation than I could have someone arrested for looking at me funny.
In fact it's very hard to dislodge a permanent employee in the public sector, ESPECIALLY a unionized employee, ESPECIALLY an attorney. They have to do a LOT wrong, a great deal has to be documented, and those forty raped virgins have to have their affidavits signed and notarized before anything can be done.
I was very disappointed in how her exit was handled. Bad writing that totally underserves a great case and a loyal audience. Boo.
A-Jock
A Tad Overinvolved in L&O-Land