Might be because FCP 7 is 4.5 years old...2.5 years since it was discontinued, and this is a newer camera. Came out within the last year, no? And every camera maker has a slightly different format of AVCHD, which makes things difficult. You are are running an old, discontinued NLE and trying to use a brand new camera. This is always an issue, and the solutions are...
1) Get an update to the NLE...only, there isn't any. So you need to move to a more current NLE. FCX, Adobe Premeire Pro, Avid (although for you I'd not recommend Avid).
2) Use Clipwrap because it works. Sorry about the no IN and OUT thing...you wouldn't be able to do that with Adobe Premiere either, because it works with the files natively, no conversion. Although Prelude allows you to do that.
3) Get another NLE...but that was part of my answer in 1.
Compressor won't help...it doesn't read MTS files. Nor will MPEG STREAMCLIP.