>>10903688ehhh it happens a lot, and having built some lego mechs, I can tell you exactly why: shoulder joints are fucking hard to make. The good lord probably went through six or seven iterations before he got one with any decent flexibility. it's a ball and socket, which can ideally RAISE because it's on hinges created by the clavicles and scapulae.. but even without that part, how do you hold the socket in place? For a toy, it's hard as fuck. In order to not just snap off, it needs something on TOP of the shoulder, which ruins the look (see also the new neca toon april o'neil figure)
And if you want more shoulder-junk sitting on top? Forget about it. they're getting pushed down to make room