Random character creation would be an interesting campaign idea, assuming you have full player buy-in. You could also do it as a one-shot, but honestly I think just making pre-gens would be better.
I actually had two purposes in mind when creating/converting these tables, neither of which were to impose them on players in a campaign I'm running. The first was for myself, as DM, for the purpose which the original tables were intended in the 1E DMG, i.e., the random creation of randomly encountered classed NPCs. The second, and the catalyst for actually doing it, was for myself as a player. I recently tried playing in some play-by-post games, and some of them have an application process that involves creating a character to submit. I felt using a random procedure like this could be a good way to spark some ideas.Where the random tables come in really handy IME is when a player has some specific ideas for a character but no real ideas on how to flesh out the rest.
For example, someone might have a great idea for an Elf with some specific personality traits, but no clue what class it should be and so rolls for its class and some background details on the random class table.
I don't have XGtE, although I seem to remember hearing that it ended up being pretty much identical to what was in the UA playtest, which I'd be interested to look into again to see if it suits my purposes.If I was going to do a set of random tables, I'd go all out. I'd have tables, followed by sub-tables, followed by more and more sub-tables. I'd go with race, sub-race, background, personality, ideals, bonds, flaws, class, sub-class, and ended with XGtE "this is your life." It would be like Traveller without the random death in character creation. Race would impact everything after it, since it would adjust many cultural aspects. The goal of this would be for someone to test the player's roleplaying ability to adapt to something that may be completely different than anything they would ever choose.
As for race, here's a full set of tables, including the chance of multi-class I posted up-thread:
Chance of Multiclass*
|Dragonborn, see subtable|
|Dwarf, see subtable|
|Elf, see subtable|
I've also made some tables for background, here.