So in the end the only defense against using this software is that it may slow down your service(most likely will) and that the places that you need to use it, you shouldn't. This is mostly true looking at the reasons ti01shadow listed. However, you cannot always know every situation. Everything isn't black and white.
For example, the whole reason I'm here is because I can't port forward. I've done it a few years back at my parent's house and it worked. Now I'm in college living in a townhome. My internet service is inclusive with my rent so I can use it how I want. The internet works astonishingly well giving me download and upload rates I'm nowhere near used to. But the problem is that the internet is provided through the town homes routers to my router.
I just want to be able to setup a server so my friends from back home can play Minecraft along with me.
This is the biggest help I have had since discovering I was behind multiple routers.
So YES this post does help whether or not I plan to use the program.