Logistics V is the most valuable skill in the game. It’s an ass to train for but when you look at the sheer scale of the bonuses on logistics ships, level V is very much in demand.
It’s also a prerequisite for Force Auxiliaries (capital logistics) which are awesome ships often relegated to alts but that can really shine in the hands of a dedicated player who can focus on managing the repair and cap modules.
As someone else pointed out, scouting is also in demand, as are cynosural field scouts — again often relegated to alts but not necessarily so.
There are also various command vessels, in particular command destroyers which rarely contribute to fleet DPS but absolutely contribute fleet bonuses and tactical options.
So yeah, there’s stuff out there if you wanna play a support role, and it’s valuable, too.