I'd say 95% of the music we listen to is 4/4 time signature, as described above. Dancehall is almost always 4/4 as is basically every other kind of club music. If you hear a non 4/4 beat that's not a 3/4 waltz it will probably sound quite weird and hard to follow. Breakcore sometimes does 5/4 and other time signatures, which usually sounds very unexpected and fucked up, which is the goal there.
A lot of people use '4 4' and '4 to the floor' interchangably, the latter refers to 4 kick drums per bar, the familiar 'oonce' sound of house, techno etc. '4 by 4' or 4x4 is jargon for UK garage with 4 kickdrums per bar which can be very similar to house but is usally a bit more skippy, often using 12th or 24th note percussion (aka swing) and more pronounced synth basslines sometimes similar to grime.
And yes, some of it is great, I know very little about it as a whole but often play Dexplicit's 'Dexplicit Dubz vol. 1' tune Bullacake, it's a very tight, colorful tune with a SICK bassline, usually gets a big reaction and is a nice tool to pick up the energy of a set with too many dark, moody half stepping grime or dubstep tunes in it. This is one of the things I love about UKG right now, between grime, dubstep and 4x4 you have a real variety of beat patterns available all at the same tempo. You've got the half step minimalism of dubstep and some grime, which can sound quite slow, the bouncier grime tunes with more fast percussion like Dex's Forward and these 4x4 tunes which sound fast but in a different more linear steady way. As a DJ it really gives you a lot more options to lead a dance through different levels of excitement.
