I tried a few VT runs with Gnome Sorcerers of MA to better see your point Lujo, and now rereading your comments I noticed you were talking about Gobbos

When you wrote about this build, you didn't mention why is it a pure caster. It's not due to laziness 'why should I bother', but more like a restriction. A MA sorcerer has unboosted health, and simply can't soak a hit from higher level guys. A sorcerer who can't tank hits... Good, 2/3 of your class traits are thrown out of the window.
Due to this, I could never get better than 1-2 level higher kills without wasting a consumable. Sure, I could have used some, but then the thoughtless play no longer holds up. Also there are quite a few monsters who do punish spellcasters this weak. Anything with increased health (dragonspawns, zombies, meatmen), magical resistance (goats, golems) or mosters with interesting flavors (cowardly enemies in corridors, cave snakes, shades, burn vipers, trolls with high health and res. etc.). If you needed the Gettindare hit for the kill, you can add firststrikers to the list as well.
Another thing that bothered me is that due to the build's inefficiency I was running out of blackspace early. Coupled with the ho-hum leveling, I had less popcorn and a lower level than usual by the end.
So to sum it up, Gnome Sorcerers are not as good in thoughtless play as you made it out to be. You may be tempted to do high level kills with potions, but it introduces the optimization of resource management between early and lategame. Misjudge it, and you will fail against your bosses. Another problem is the blackspace running out early, which could leave you stuck at low level being unable to do anything.
Some dungeons could annoy you with their gimmicks too. A labyrinth blocking you off while trying to refill mana. Getting boxed in by mana burn plants or newly formed walls in SP forcing you to waste popcorn/Dings.
Now let's move on to the Goblin variant. You may have not noticed it, but choosing a Goblin is the best way of covering most of the weaknesses of the Sorcerer MA combo. The Goblin bonus helps directly solve the exp situation, and if used to set up dings during high level monster kills, it creates bonus xp too. You don't have to waste your glyphs either, convert something from the shops. The constant dinging will make sure you don't waste much blackspace either.
But is it a thoughtless combo? No. You interact with less of your class features, but you need to play your race at higher efficiency. The Goblin bonus is easy to misuse, players who want to succeed need to realize it's best used granularly in setting up level catapults.
In my eyes it's just like a caster version of playing a Taurog Berzerker. Simple, but not foolproof. Taurog has Goo as an obstacle, MA has the SMM. Though have you tried Taurog Half-dragons? They sidestep every possible problem. I guess it's the same with MA Bloodmages.
I'm interested in your response Lujo, did I miss something important now?
@Tinker
I like all your ideas, but only the 1st is workable. The 2. is broken with B2P (more than any god boons, and they are limited and need dedication), the 3. is not simplistic enough.
@Everyone
What do you think about the usefulness of Dwarfs? Also do you have any reliable VT strategies for them?