I thought GW was doing monopose these days? I guess the guard is too old for that.
modern monopose complaints are sometimes correct, sometimes wrong(some people bitch about things being monopose as being a lack of weapon/arm/head options, which just isn't always the case). The easiest way to explain it would be with some examples.
Old tactical marine box. You could rotate the waist slightly and move the arms a little lower or higher, whoopdeefucking doo. It still looks dumb having 50 space marines with some variation of pointing slightly left, slightly right, slightly up, or slightly down while the legs are all in a squatting pose.
Modern space marines. The poses are dynamic and varied. The problem is that a box of 5 minis will have the exact same 5 poses, if you're building a unit of 20, you get 4 that match. In some boxes where it's a box of 10, there aren't 10 unique poses, it's usually still just 5(there's a couple where it's even just 3) unique poses. These would be monopose.
Another monopose complaint that's usually incorrect would be something like bladeguard veterans. 3 dudes, the kit comes with 7 or 8 sword options alone for sheathed, 2h, 1h, wiping the blade with a cloth, and on and on. these are great.
Monopose with options where it's a problem with be the new ork boyz kit, where for some fucking reason GW didn't include enough shootas and choppas in the box to actually equip the squad with one or the other, so you have to do a weird mix(this was so bad that they cancelled discontinuing the older ork boyz box because people actually hated it that much).
This goes with the previous part. I've not tried gunpla myself, but they supposedly leave GW and western companies in the dust.
Bandai is willing to avoid cramming as many parts onto a single sprue as physically possible, and will have them laid out logically or with enough space between the parts to be able to quickly find parts on the sprue, and even labels the sprues so the parts will be A1, B15, C5, etc so you know which sprue to even pick up before you start looking. GW rarely labels sprues, and will usually just leave everything a mess on them in no particular order because whatever program they're using decided having all of the guns next to eachother would be great except also fitting in half of a left leg over there makes sense too.