To address your complaints: One of the glaring weaknesses of joker is starting his offense in the first place. Specifically, he has a low B1, sweep D3, and ranged D2 to use in the neutral.
So how do we start this offense? Well, Joker has no overheads (I guess you can say B2 but it's really slow and doesn't give joker much). Therefore, an opponent just has to block low until they see a jump in. Going more in depth, even if you're lucky enough to get a B1, that can only be followed up with crowbar or B13 (mb gun would be nice but it has whiff issues!!). Crowbar no longer otgs, and both of these enders don't lead to anything by the joker. So no offense after this, just back to the neutral, where joker does not excel at all whatsoever
Okay, so what about D2. You can do D2 teeth, which is pretty much pointless unless you got them near a corner. Most of the time, it's pretty useless because walking back will most often negate the teeth. You can do D2 MB low canister, which can easily be jumped out of and punish us instead. Even if they respect MB low canister, they butchered our + frames anyways so it gives us, again.... nothing. Right now, D2 Crowbar is our best option, but as discussed earlier, there's no otg.... so we get a dash and then back to neutral.
Not much to say about D3. It's a sweep. At certain ranges it can lead to an ambiguous J2, but that can easily be countered by backdash or wakeup.
NOTE: These aren't mu specific things. This applies to every character in the game. Every character can easily counter us because it is excruciatingly difficult to get offense started in the first place.