In LR it is one check box that needs to be checked...
I agree with this.
But I'll also add something else here: optical perfection comes has costs. Sure, we all want perfect pictures straight out of the camera, but you have to keep in mind a few things:
1. Money. As in $$$$. Instead of spending $1000 on the 24-105 and getting this:http://www.photozone.de/canon_eos_ff/420-canon_24105_4_5d?start=1
You could have spent $2000 on a 24-70 Mk II and gotten this:http://www.photozone.de/canon_eos_ff/773-canon2470f28mk2ff?start=1
How much is a straight horizon worth to you?
2. Utility. Instead of having image stabilization, autofocus and a huge zoom range you could have spent $1,700 and gotten this:http://www.photozone.de/canon_eos_ff/713-zeiss25f2eosff?start=1
Do you want to walk around with a bag full of primes and change lenses every 10 minutes to get a perfectly straight horizon?
My point here is that every lens has its tradeoffs. Some trade performance for cost. Others trade utility for ultimate image quality. What lens is right for YOU is what you need to work out.
If you're going to be taking nothing but pictures containing tons of perfectly straight lines (ie architecture photography) you might want to invest some cash in some primes that have as little distortion as possible.
If you're going to be taking casual travel photos that occasionally show distortion effects (like your shot here) it's probably better to err on the side of utility (like you've done with the 24-105). What good are perfectly straight lines if your dog runs off while you're trying to change lenses??
Finally, a tip: learn the strengths and weaknesses of your gear and keep that in mind while you're shooting. Don't try to force a tool to do a job it wasn't made for....