Yeah, summoned bags don't reduce the weight of coin or the gear you're wearing, and since STA is not a good investment for a cloth caster, I highly recommend putting points into STR as a Magician or Necromancer and maybe even Wizard. Enchanter is a different story, though, since they need high INT and even higher CHA in order to be viable. Plus they can buff STR innately.
Yes, racial hide will dismiss your pet when it succeeds, but it is an invisibility with an unlimited duration and lacks the chance to break early, so if you ever have a moment when you would normally invis and AFK to med or wait for a spawn or something, hide becomes superior to invis (once it successfully activates). For instance, I use it when I'm sitting LFG at the zone in and don't know how long I'll be there and might step away for a moment.
So races with hide (Dark Elf, Wood Elf, Halfling) have an advantage over races without hide under most circumstances. It's not so important for classes that get hide (Rogue, Ranger, Bard, SK) or
Improved Invisibility (Wizard, Enchanter).