Let's see if I can explain this better: there are basically two types of newbies -- the players familiar with FPS games but have never played paintball2, and the players who have never played FPS games at all. I'd say that most new players probably have fair experience with FPS's. They've probably at least played the Counter-Strike mod or UT2004.
Let's take a look at CS for a moment. I'm not a huge CS fan, but it's the most popular online FPS for a reason, and while I'm still curious as to what that reason is, it isn't because it's newbie friendly. In fact, I would even go so far as to say that it's the most newbie-unfriendly FPS game I've ever played. You have to buy better guns and equipment to be able to kill people more easily. You have to have money to buy equipment. You have to kill people to get money. Argh! How am I supposed to be able to kill people if I don't have the money to buy better equipment to kill people with to get money to buy better equipment!? Not to mention the fact that there's no respawning. Once you've lost in your pistol vs. aug battle (because you couldn't afford a gun), you're out until everybody else is dead or the 5-minute time limit is up. I'm not saying I like this, and I'm not saying we should make the game like CS. I'm just saying a game doesn't have to be newbie friendly to be popular.
So we've established that it's not the newbie-friendliness that makes CS popular. Let's take a look at some of the CS maps, then. Dust? Multiple paths. Dust2? Multiple paths. Office? Multiple paths. Assault? Multiple paths. In fact, every last one of the major CS maps has lots of routes and sometimes even multiple locations for various goals. Hell, lots of servers will even run the same map 24/7. Why? Because the design of the map allows for unique gameplay every round. We need maps like this. Maps you can play for hours on end and not get bored, as opposed to the boring-after-five-minutes-spray-and-pray-autocockers-in-a-box maps that are running rampant now.
Now what about UT2004? I'll just say this. If you have it, load up one of the 1-vs-1 maps. Notice that it's about 5x's the size of pbcup, a map often played with 10 people. Do the math: 5x's as many people, 1/5th the volume. That means we've got like 25x's the player-to-map-volume ratio professional game designers of a popular game feel is appropriate. In other words, we're cramming way too many people into too small of an area. It removes many gameplay elements as players might as well just spray -- they're more likely to hit something that way. There's no sense in using any strategy as the whole thing is just one big clusterf*.
Now, you say these "newbie friendly" maps are good in moderation, but there is no moderation. Refresh the server list. 3/4 of the servers are running pbcup, theice, or some other crappy, small, 1-path, or autos-in-a-box map. Now I've gone off on a bit of a tangent here, but my initial point I planned to make was this:
These small 1-path maps aren't really newbie friendly to the first type of newbie, which I think is the majority. Newbies with experience in other FPS games may not be able to aim a paintball gun well, apply the proper lead, etc., but they can use strategy learned from other games to get the jump on other players... or can they? They can't if all the bunkers are transparent! They can't if the map is so small that there's only like 2 strategic locations and people spray there every round! They can't if the map is just a box!
The thing I was agreeing with eiii about is that it brings up players wrong. Players come up thinking that to win the game, you just spray, or that you don't have to think, just shoot whoever's in front of you. They get in this mentality of playing, and when a good map comes up, they think it sucks because they have no clue how to use strategy and end up getting railed on. Unfortunately they're the ones that complain the loudest, and pretty soon 9 out of 10 servers have these crappy maps in rotation. The other players simply sit in silent protest most of the time or move onto another game. And skilled new players blow off the game completely. Sad thing is, many players haven't even seen some of the better maps because they're not in rotation on most servers.
Anyway, I have to go. Sorry if my rambling was incoherent.