(This post is not legal advice, consult an immigration lawyer, etc.)
Yes and no. TN is technically only for specific professions drafted in like the 80s or something. It's incredibly stupid. For example, many Canadians use "Computer Systems Analyst" for their TN which explicitly forbids programming, as a programmer is not considered a professional job in the eyes of NAFTA. It's bananas. If you don't have a decent secondary education with a recognized degree, you're likely out of luck.
And while yes, you can effectively ride TN status forever, it has a lot of downsides. For one, it's not portable, so you have to restart the process if you switch employers. In theory you can't even seek employment while on a TN. Two, the customs agent letting you into the US can decide at their leisure whether or not you qualify. It's rare but I know of a few instances of people getting rejected for no real reason. If they think you are abusing it, they will reject you, etc. If you lose your job for whatever reason, you have to leave ASAP. There is not much peace-of-mind with TN status.
Compare to an H-1B, which confers a ton of benefits, like a straightforward path to a green card (also possible with a TN but a lot of lawyers are less comfortable), easy to switch employers, your employer must pay for everything, if you're fired your employer has to pay for your travel, there is a lengthy grace period where you can be unemployed to either find work or wrap up your affairs, you can stay in the country while waiting for approval, etc. It's a million times better than TN.
Attorneys probably also dislike TN status because they really are not necessary. The applicant, not the company, must pay the application fee. In theory you don't need lawyers at all, but it is pretty useful for them to prepare the documents and cover letter for you. Get your ducks in a row, etc.
Most Canadians I meet in the US who are on TN status or H-1B visas are, at least initially, on the path to a green card. Most half-decent employers who are willing to sponsor want to put you on that path anyways, since it ensures your position is not going to evaporate because you were denied at the border or something. Most people on non-immigrant or immigrant-status visas want a green card anyways, so it is sort of the default path.
Lastly, most folks do not know about the downsides of a green card, such as the frustratingly complex tax burden if you are abroad, that it expires if you leave for ~5 years, etc.