I'm not sure about anyone else, but for me, I have no difficulty hitting the leaderboard. I only recently took up shoddy in the last week, and Ubers in only the last 3 days, which has become my favoured Metagame. I already have 1 alt, Twinks, sitting at 16th position with 1600+ CRE. Heck, even my test account is doing well, and I only use that when I'm testing gimmicky things, such as Ho-oh lead (I figured Sacred Fire could Ruin Deoxys' Sash, threaten Scizor/Forry, etc, but enough about that).
IMO, aside from the major time lag, and the constant repetition of the same 2-3 opponents if your lucky (which I enjoy as the rematchs are quite fun, somewhat intimate), I believe there are two main factors that influence the relative unpopularity of Ubers.
Firstly, theres the centralisation. While I agree, that plenty more things viable in Ubers than people give Credit for, most people still probably think that ONLY Ubers are viable, and for anyone who has scrolled down Scizor's page, maybe Scizor alone as a Non-Uber, aside from the obvious Blissey. That being said, once you understand that many OU, and even lower pokemon can fill niche roles in Ubers, one has to understand that these niche roles, while taking the newbie completely by storm, an experienced player generally knows exactly what something will do when it shows up. For instance, I played a guy today, who was suprised to see Ludicolo in Uber play, after hit lead T-Wave Kyogre killed my Darkrai. He T-Waved, expecting some sort of swift swimmer, and I Leech Seeded. He had absolutely no idea what it would do, so I sat there Leech Seed stalling him and eating his Thunders, until I grass knot, and it dies. An OU or UU player sees Ludicolo as potent rain sweeper, an Uber veteran sees it as a counter to Kyogre and a makeshift Special Wall in rain.
Secondly, people don't understand that in Ubers, unless you go out of your way to find a counter, such as Ludicolo for Kyogre, there are pretty much no Counters to anything, given the ridiculously powerful stats, and insane versatility of any Uber not named Wobbuffet. Technically Kyogre's "counters" can't even counter it reliably. With SR and SPikes up, Ludicolo may be unable to handle 2 Specs thunders, especially if it gets paraylsed and can't protect. With SR up, Scarf Kyogre's Ice Beam can 2HKO all but the bulkiest Latias before they can recover or Thunder it. Specially Defensive Dialga can be 3HKOed and outsped by Kyogre's Surf and it cannot withstand Specs Waterspout. What I'm trying to say, Ubers is about countering a few things, and Checking as many threats as possible, a concept with OU and UU players do not understand well. The closest thing that can perform an Uberesque single turn set up and Sweep in OU is Empoleon, and its been the subject of many a Warstory, simply because its rare in OU for a single pokemon to be able to tear its way through an entire team. People don't like a meta where a single misplay or miss can cost you a match. Half of the stuff in Ubers can sweep you in a moments notice, and a newbie will have no idea how to handle this.
IMO, the best way to popularise Ubers is more warstories, and to use tools such as the Smog to draw attention. IMO, updating the analysis of pokemon semi-viable in Ubers might catch a few people's eyes. I have to admit I was almost suprised when I didn't see an Ubers analysis for Foretress (granted, its pretty much the same thing as the Specially Defensive set).