I have a fix for this issue, it works, but its annoying as hell. The best answer would be for everyone to petition facebook to cut it out already, but thats not likely to happen, so here it goes.
Step 1. Go to a contact that is having an issue (a contact where the +1 is appearing before your phone number.)
step 2. Edit the contact (note: you have to have created an actual contact to do this, a contact that is only imported from facebook without a card on your phone is not going to be able to be editted)
step 3. Create a new phone number (using whatever their phone number is) and code it as a home#, not mobile. save and exit edit mode.
step 4. You should now see the home # there without the +1. Long click the home # and set it as the primary #.
Step 5. Edit the contact again, and switch the home setting to mobile. Delete any other contact #'s in the card that you don't need (ex: #'s linked from google). Save and exit edit mode.
Step 6. This should have fixed the problem, given you a new primary # without the +1, and given you the ability to text to that # without a problem because it is now coded as a mobile #. This fix was tested on an HTC Thunderbolt on the Verizon network. I'm going to assume it will work somewhat similar on other devices. I hope this helps.
EDIT: This process, as far as my contacts are concerned, has not only given me a # i can actually text to, without the +1, but if done this way, has actually removed the # with +1 from the contact card entirely.