I actually don't mind the lack of a trailer and I can see a few different reasons why this isn't a bad way to go.
Firstly, about 4 years ago, I got screwed over buying a couple of Encore Convoys on eBay which were advertised as pristine but when I got them the cabs were screwed over by really bad water damage (as an aside, when I mentioned this on another TF forum, the general response from people was to the effect of "Is that a-hole still at it with that scam?!"); what really sucked was I bought one to be my wedding cake topper and the other to put away down the track for kids.
But I digress.
The trailers and accessories are largely fine, but the cabs are fodder, so this reissue works great for me. Likewise, for anyone who has a good trailer, but damaged Prime cab, this reissue is just what the doctor ordered.
Secondly, let's be honest- trailers are a pain in the tail to display and if we're honest, we tend to store them rather than display them when space becomes an issue. This way, the figure can be displayed and the trailer becomes a non-issue.
Thirdly and finally, if this is how much he costs without the trailer, I shudder to think about how much he'd cost with a trailer, not to mention that the missiles and launchers would be completely nerfed. A cheaper Optimus gives both collectors on a budet, and parents buying for their kids, a much more affordable option when it comes to buying a G1 Optimus Prime.