V20 [also called '4th Edition'] is a lineal descendant of the games since 1st Edition in 1991. Same for the three big others [Werewolf/Mage/Changeling], a player familiar with the older versions can get up to speed very quickly - I'm actually right now playing a Mage game with an ST who's using mainly 2nd materials while I'm using 4th and the main arguements we get into is that the Abilities are a little bit different. You can't do that with 5th.
*dingdingding*
Which was the key problem. If you wanted to play a more 'localised' and less 'ideological' vampire game where the Deus Ex Elder was much less prevalant and with much more mystery [a lot of Requiem was splats full of 'wierd and wonderful creatures' that an ST may or may not have in their world], you can play Requiem. Vampire 5th tried to ape this while ditching some of the unique selling points which made Masquerade, well Masquerade [as well as ditching backwards compatability] - for example, the 5th Camarilla was quite clearly morphing into the Invinctus. In my opinion, it would have simply have been easier to produce a 'Masquerade/Requiem Conversion splat' where it lays out how Requiem setting/mechanics system can be grafted into a Masquerade game and vice-versa.
Yes. Masquerade [as well as Mage/Werewolf] really needs a player 'quickstart' book for players only. I think they exist online, but I've not checked quality of. A player doesn't need the 600-page doorstopper, esp if the ST is handling all the rolls etc.V5 has issues with a very narrow definition of 'street level', and V20 suffers from the book being 600ish pages long (being made as a 'one and done' tome for existing fans). Which is an issue with all the 20th anniversary editions, M20 is half as long again.
Masquerade [and the games off it] isn't much better. Odd 'compartmentalisation' of knowledge [wot, I can only roll Academics or Occult?], Firearms with no perception requirement, a situation where being more skilled equals worse results [all about Secondaries] the odd Awareness/Alertness situation, slightly different Ability sheets for different games etc. Every ST I've seen over 15 years has had to do a little bit of homebrewing to get it to work less stupidly.
You get this if you've 'played around with different WoD games too. This was me recently.
Me: 'Roll Intelligence/Finance; is any of the gear here valuable [and so worth stealing?]
ST: 'What's Finance?'
Me: *looks at sheet* 'Crap, this is Mage, not Vampire!'
[Cue five mins argument to where Finance now lies in a MtA sheet]