This is pretty much straight forward as a strong request for an update.
If this was previously mentioned or was considered, please ignore this.
Please edit the Armor Stand that has another variant. Keep the main variant, but the new one with arms. This is no joke, Minecraft actually has armor stands with arms. Adding arms in Minecraft is accessible with commands. Another armor stand feature is being child sized also via commands. Here's a quick picture I found as evidence. Please add the arms option/part?