Leave it open.
I'm going to start this answer in a controversial way, by quoting part of the site tour which actually doesn't usually apply here on Puzzling:
Focus on questions about an actual problem you have faced.
Obviously, this guidance is much better suited for sites like Stack Overflow or Software Engineering or Parenting than less practical sites like ours. Most Puzzling questions are not at all related to actual problems in real life, and are more about having some fun creating and solving puzzles together. However, this sentence reflects a philosophy which drives the Stack Exchange network and which was originally, at its foundation, the driving force for this site too.
Puzzling SE started off as a site for questions about puzzles, and early questions posted here include, for example, What is the maximum number of solutions a Sudoku puzzle can have? and Why is a single-corner twist not a valid position on a Rubik's cube? - theoretical questions about the nature of certain types of puzzles. After some very bumpy months in 2014, our site and community shifted largely away from these types of questions, and towards "questions" which are puzzles themselves, with "answers" which are attempted solutions. But there's still a place on our site, albeit a smaller one, for questions about puzzles, including practical ones based on real-world puzzling problems: meta consensus has always been that these questions are equally welcome as questions that are puzzles.
I believe it was an ex-moderator of this site who once made the very thought-provoking observation that, if the original purpose of this site was to help people learn about puzzles, then it's actually achieved that purpose in an unexpected way, because we learn by doing. (They expressed this better than I can, but I can't find the exact quote now.)
Why am I blathering on about ancient history? Well, the question you're asking about is ancient itself, asked in the final hours of the site's private beta stage. But more importantly, sometimes it's important to step back and remember who we are, how we got here, and why we have the rules we do.
Imagine you're a Rubik's cube enthusiast who wants to learn more about cubing. What would you be looking to get from a site like this? We have some questions about how to solve specific positions or whether they're achievable, but those are mostly of quite limited interest, useful to the OP but not so much in general. We have some questions about terminology or optimal/extremal positions; those are interesting but not so much practically useful for a cuber. In a very quick glance through our rubiks-cube posts, this was the most actually-useful one I could see. How best to scramble a cube is a basic problem which any cuber might wonder about, and surely a useful FAQ for any site hosting Rubik's cube questions.
The other answers on this meta so far are both focused on the highly theoretical nature of randomness. I'd rather focus on the practical problem which might be faced by real cubers every day, and on the useful answers which provide: (1) an officially approved program and online interface from the World Cube Association which they use for "good" scrambling; (2) a caution not to bother overdoing the number of twists, with an approximate upper bound on the necessary number for a "good" scramble; (3) another online tool, without much commentary; (4) another answer which basically repeats points from 1 and 2.
- Can these answers be improved? Quite possibly yes.
- Do the answers contain useful information for an average beginning cuber? Surely yes.
- Is the question itself a useful one for cubers to know the answer to? Absolutely yes.
I submit that it doesn't matter that true mathematical randomness is almost impossible to achieve in real life. On the other hand, an answer from this theoretical, mathematical, point of view could potentially make a good addition to the set of answers already existing on this question. But such pedantic mathematical points (and I say this as a proud pedant and pure mathematician myself!) don't mean that the real-world problem is useless, even if it's not solvable in an ideal mathematical sense. It's still an actual practical problem, and our site is richer for hosting such information about it.