Sure, skellies are weaker now. But that does not limit their effectiveness, it still costs one attack to kill them. And if you feel just dumping skeletons at the enemy feeds them, use spectres, a newly born vampire should be capable of casting them. Anybody can squeeze out 2 xp from civics if all else fails (Alexis without form of the titan).
As Calabim have good production, Soul Forge is not difficult to get. That's 1 death mana. Nox Noctis and Stigmata on the Unborn give entropy and shadow manas. If you don't have the holy cities, conquer them. Then get chaos mana and build necromancy tower. You now have 2 death mana. Then make some death nodes and now your spectres become scary. Of course nobody wants to meet a stack of 150 vampires on the battlefield, but if they hang behind 150 skellies (which you have to kill all) and attack with 150 spectres, it will hurt your own SoD, which is not quite as big as Calabim have lots of production. And surely that stack has some neatly promoted vampires as too to mow down even lightly wounded targets. They can also cast regeneration on the whole stack, so their city raider III vampires have all the advantages of march. And they can give regeneration to support magi and disciples. And it is not a big deal if their regeneration caster dies as they have plenty of reserves.
It is not the size (strength) of the skeletons that counts, its the number of them. And killing them in defense nets very little experience for powerful units. Getting that 1 extra promotion, say cold resistance to handle tsunami better, for one or two units (they are out of more important stuff to get) while losing a combat V, drill IV, city garrison III, shock II longbowman is not a good deal IMO.
Killing Hyborem early, or having a nice Elohim player do lots of Hallowing will allow you to reap the benefits of StW without other drawbacks than Basium hating you and dragging all of his goodie buddies to suicide against you. A big population = lots of vampire food + lots of production = SoDs of nasty vampires.
I am also well aware how Calabim die next to Tasunke. Everybody seems to. But Calabim are supposed to suffer early and then rise to dominance.