I pre-order for the bonuses. You can get as much information out of beta testers as you can out of reviews and such. Every time you buy a product/pay to see a movie or anything such, you're going in there blind. You can get informed by external sources, but that doesn't mean you know anything about the product yourself, just that you trust those sources on what they're telling you, in which case you can get the same quality of information out of beta tests, marketing, watching gameplay videos and such (hell, some games will let you beta test and see for yourself if you want to pre-order).
No, it's not stupid. It's designed for people who KNOW they're gonna get a game even before it's out. They can know that based on several things and if they know what they're doing, they're not really at a big disadvantage against people who buy things on release day or later, unless you're the kinda person who waits until someone else gets a product, check it out for yourself at their place, then buys it.
For example, I can tell you I preordered Battlefield 3. I knew it'd be a game I'd buy and one I'd buy on release day. I've gotten to play it in an open beta, but even based on history/videos I could pre-order and know it's not a bad decision, because it's just the kind of game that would have to do a lot to disappoint me to the point of me regretting buying it.
Same for TOR. Now, to be fair, I'm not as pleased with TOR as with some other games, but I also don't regret pre-ordering/buying it. I wanted to play it and enjoyed it for a good while. It's not exactly the MMO I'd want to keep a sub active for, but as a purchase, it's not something I regret (something I wish I could say for my stupid decision to buy a 6 month sub right away that's now gathering dust)