It depends on how well I can comprehend the Shakespearean dialogue. Also, it really must make sense in-universe. When I remembered reading Shakespearean English in high school (and I'm a very avid reader), I would often get really strange meanings from the text, until I read the side notes that said "This is what they mean here" So, dialogue like that could easily lead me on wild goose chases, which I'm not fond of. In that version of English, a lot of colloquial constructions and phrases mean VERY different things than we think they do.
The whole "Blood is thicker than water" for example? We have it precisely backwards. The intent of the original phrase was that shared water (as in brothers-in-arms in the military) means more than heritage --- which it absolutely DOES in the military.
If I take the original Dragon Warrior had a faux Ye Olde English feel to it, which was kind of cute. But at least I could understand what they were saying. If a game just had old fashioned dialogue and I couldn't understand the dialogue, I would stop playing the game.
The real key is that whatever the NPCs and players say must be understandable to the player. It would be the same if, say, a Star Trek universe RPG had Klingons speaking (and writing) actual Klingon. While it makes perfect sense, in universe, it would annoy players who weren't fluent in Klingon. Another example would be me trying to play a JRPG still in its native Japanese. Even a bad English translation is far more useful to me than great Japanese text, since I'm not fluent in Japanese.
Now, a case in point is that J.R.R. Tolkien was so in love with languages, he created his in-universe languages and wrote the Lord of the Rings saga solely to use said languages. And it certainly did NOT hurt the fame or wealth he received for the novels. Of course, in his novels he could explain the language in detail in an appendix and make sure the word's meanings were obvious from context.
Clarity is important. If you can do that with unique languages, that can really add a unique flavor to the speaker(s) using the language. But if you don't make the meaning clear, it's more trouble than it's worth.