I think the general notion of cap ships requires workbenches. The stated premise for the benches was that all components can be repaired by players if they have access to a bench. So inclusion of a bench is a big deal. I think thus far the only ships in game intended to have benches are the Carrack and 890 Jump. If you don't have a bench you have to repair in your hangar, so long duration craft really offer something very useful. You can overclock your Polaris guns, thrusters, shields, etc. and be fixing them daily while out on a month long excursion; but this requires players' time and effort in game. They're making Engineering a real station to focus on.
Workbenches are an integral part of the wear/repair and overclocking dynamics. They can't get rid of one without the others.
BTW, I also recall hearing recently that the reason they took the third engine off the MSR was so they could open the bay enough to get an Ursa in. So yeah, it should fit an Ursa.