I think there are several issues at hand.
First as Unorthodox said, there is a dangerous precedent set here. A similar precedent killed what was original sample-based hip-hop in the late 90's - early 2000's. Please read everything and hear me out, I will get to my point:
The fact is, hip-hop started off jacking beats. The artform started as people rapping over funk beats in the late 70's and various derivative instrumentals in the 80's. The artform continued its sample-based heritage into the late 90's, with people from Dre to Puffy using samples in hit song after hit song.
Then came the hammer came down. The artists who initially created the music from which the samples were taken (the sample-rights holders) started extorting the rappers. Prior to that, it was a happy medium of sorts. But around the late 90's - early 2000's, the rights-holders started asking for 80% or more of the royalty of a sample based song.
This greed killed it.
Producers then moved to techno synth-based hip-hop we are plagued with today in order to move away from the extortion of the rights-holders. The move worked from a business perspective, but -- in my opinion -- was bad for hip-hop as an artform.
The mixtape was an expression of hip-hop as an artform. Original rights-holders were never intended to receive a royalty. The mixtape was a form of promotion, something not to be taken as seriously as an album, but something that contained a similar gravitas as an album, for it was a pure expression of the artform.
As mixtapes became more prevalent, especially with 50 Cent's revolution of the mixtape from a something people rap over to the actual construction of an entire song from a direct and purely derivative work (someone else's complete beat) it became not only a promotional vehicle, but another way to give people a taste of what an artist's LP could feel like.
The difference between the mixtape and the LP during the 90's and early-mid 2000's was one thing... and one thing only:
Distribution.
The LP was distributed to record stores, department stores, CD clubs (remember Columbia House?), marketed and promoted by the record companies with large budgets and national press.
On the other hand, the mixtape was not distributed in this fashion and was available only to hardcore fans or people who had access to the mixtape from people promoting it on the streets and in clubs.
Today, I believe we've come to the point where the mixtape and the LP have the same weight not only artistically, but also through distribution. The internet changed everything and this is another example. Mixtapes can be marketed as easily as the LP via the internet -- and the fact that it's free, can give it a greater reach than the LP itself. With this type of easy promotion, the beats which were previously seen as harmless in the pre-broadband world of hip-hop are now of high value, because of their reach and the benefits reaped by artists like Mac Miller from a successful mixtape. Thus, because of a change in distribution, there has also been a change in the perception and consumption of the mixtape by the public.
Sure, it is within Finesse's legal right to sue, the $10 million mark tagged to the lawsuit is to create publicity and to force Mac Miller into a settlement. I doubt Finesse will get anything close to that, but what happens is that this precedent will hurt likely hurt hip-hop as an artform.
The question is, with such a precedent, where will hip-hop go next? More lame David Guetta-like tracks?
There needs to be change, and this lawsuit doesn't help the artform, although Finesse is on the right side of the law on this one.