Bethesda has barely had two months time to patch and they've already patched Skyrim more than two times since release. The only thing fallout new vegas had was the interaction between factions and not even then were all factions joinable. At least the thieves guild in skyrim has infinitely quests, as does the companions and the dark brotherhood, but in fallout new vegas there was only very few quests for some of the factions, or none at all.
Joining factions isn't the point in NV, it's the interplay between them, how you can alter their opinion of you, how you can affect them, and how you'll inevitably make enemies of them. Most quests have multiple ways to solve them, and even different ways to end them, which can in turn affect the faction as well. For example, you can blow up the Brotherhood of Steel's bunker, replace their elder, help fix their vents, and/or help them call a truce with the NCR. Skyrim factions? You got one linear set of quests to do, usually only one way to solve them, and seldom do you ever have the ability to affect the faction's future. There are occasional choices, such as either joining or destroying the Dark Brotherhood, but those are the exception, not the rule.
Furthermore, all of the factions and their associated quests in NV are strongly linked to each other and the main story. For instance, take the Powder Gangers. They're a gang of NCR convicts originally meant to be used as manual labor to help develop the Mojave. But because its forces are too spread out dealing with the Legion and other threats, NCR lacked the manpower to control them, allowing them to escape. That's just one example of the linkage between side factions and quests to the main story.
Meanwhile, in Skyrim, as the Rat put it, every faction more or less exists in its own little vacuum, disconnected from the larger events. Dragons are laying waste to the countryside, civil war is brewing, but all the Thieves Guild cares about is some stupid bee farm on the outskirts of town not paying its dues. The subject of dragons doesn't come up with them at all, even if by all rights it
should, considering said farm looks like it could be vulnerable to a dragon attack. Or how it could potentially end up a target for either the Imperial Legion or Stormcloaks. Or...something along those lines. But there's nothing.
But...at least it has infinite quests...all fetch quests with not even a modicum of story or plot. That's, uh...very interesting indeed.