Then I guess it makes sense that the fluff pretty much states outright that the class was considered something of a failure. This would be one of those designs that make sense during wartime, where they can fill a highly specialized role adequately (and, more importantly, free up the more versatile ships for more important roles), but which aren't ideal for peacetime duties. After the war ended, the colonial fleet probably decided that the support intensive ships like the Sobek should be replaced with more versatile ships (like the Valkyrie).
I guess ships like these are perfectly capable of doing minor repairs on their strike craft, but do not possess the manufacturing capabilities of Galactica, meaning that they can't do any major repairs, or produce new ships on their own. Again, it comes down to the operating conditions they were designed for, with support being easily (and securely) reachable at any time.
EDIT: Another thought: The Sobek does seem to be less manpower-intensive than the Galactica, with more emphasis on the shooters, and less slots for mechanics. I guess that the colonial military did have to operate under rather tight manpower constraints, with experienced mechanics/technicians being in high demand. Having a design like the Sobek, which relies on a centralised support structure, would be somewhat logical, as one support crew can support several combat ships.