OP, I actually support the "Letting Thessia burn" idea, just probably not for the reasons you stated. Doing it for the reasons to secure resources for humanity though is just changing the hands in which the monopoly resides, when Thessia could become a multicultural/multi-specie world and make everyone happy. Except the Batarians. We don't like them.
If I'm forced to sacrifice some of the homeworlds in ME in order to save the whole, Thessia is first. Why? Its not because I have a grudge against them, or that I don't like them. The Asari are the most survivable species in the known ME universe. Sure, it would be a tragic loss of life, there's no denying that, but its not like it means every Asari in existence will be dead. It usually takes a species more than two individuals of the opposite sex in order to sustain a growing population without too much inbreeding. How many do the Asari need? Just one. Give it a few decades/centuries and their blue butts will be shaking at every strip club in the Milky Way once again.
I don't expect the Asari to have the same views of optimism, though. I'd imagine they'd be angry if you made them into the sacrificial lamb....