I was going to just reply with an idea, but I realized that it was basically an entirely separate suggestion.The multiple-of-4 nature is sort of ugly, though. It would be nicer to think of it as 127 "points" you can allocate, rather than 508 "bundles of 4 points each" you can allocate.
But the problem is that every other guide talks about them in terms of 510 and 252 point limits, so if we changed how our teambuilder worked, all the online guides would stop making sense.
I think it would be possible to come up with something sufficiently easier to use that we'd prefer it over the current system, but it would take a lot of in-depth design work, and thinking through all the edge cases brought up (every 4 EVs can increase your stats by either 0 or 1 at lower levels, or 1 or 2 at higher levels).
At any point where a new player might get confused, have a little Meloetta or question mark Unown that will display tips when moused over. This can include explaining the aforementioned EVs (combined with IVs and Natures), why some formats appear in the teambuilder but not the main page's format selector, and that it's possible to type commands in chat boxes.