Hi, just wondering out loud...

I recently got a job in the US and the employer is bringing me in through a TN visa (they paid lawyers to do it, etc.) I'm excited for a change but wasn't thrilled about the TN situation because I'm not interested in temporary work...I want a deep career, something long term, which doesn't exist in Canada. Considering any time spent in the US on this visa counts for nothing in terms of emigration, and you are practically barred from freelancing/earning extra income, I was wondering why people covet it when you are extremely limited and have to eventually, at some point, leave.

Is it to work for a particular job/employer and get a foot in the door?
Catch a quick buck for some time?
Is it to live in a particular US city?
Is it something else?

Just curious what it means to others, and if there's something I haven't thought of/considered in my particular situation.