Bad legal advice will keep you dealing with the legal system for much longer and at much greater cost. Something being cheap and quick upfront doesn't mean it will be cheap and quick by the end of the process.
Maybe, although I would be extremely hesitant to extrapolate from this one study and trust my legal life to an LLM. One thing that's worth noting, though, is that regardless of the quality of objective legal advice in the abstract, for a lot of smaller scale stuff the human connection actually is literally what is important. There are ambiguities in the law, which are not resolved deterministically but rather at the individual discretion of judges. Your lawyer, if they're any good at their job, knows the local judges and how they're likely to rule for given circumstances, which can influence their legal advice to you specifically.
The legals system is structurally based around manipulating text and its relations. It seems to me that the entire legal industry is the ideal use case for LLM's to take over.
Of course the legal system can gatekeep forever by design.
A bit of extrapolation from the study, but not a crazy stretch.