I would still support pre-ordering games, as it's one of the most effective ways to get a game on Linux.
However, it's a different case when the company is failing to deliver the product after they'd decided on one... but I hope the best for them, still. Nothing will get better if one doesn't.
I would support pre-ordering where it's merited. Runesoft actually did a decent job with their work on Deck13's titles. If they floated a pre-order on the next one that's in development, I suspect I could be convinced to consider doing a pre-order. Proven track record (on these titles at least ;)) so they get given the benefit of the doubt.
Other studios... Depends on the reputation of the studio and if they're honestly doing the work. Epic, until this little debacle, would have been on the short list. Id IS on the short list if they choose to run it that way on IdTech 5.