I don't see that the "machine" would make the process less labor intensive. Besides, baling hay by hand has been done for many many decades by farmers world-wide so other than the idea of an actual hay-baler (which is a LOT of machinery normally) I think this works well - and agreed that there's no reason it shouldn't work like a signpost, internally (in game code) it could just destroy the straw-object (saving memory) and store a unit value that has the quality, when it's removed that unit is taken out. Also, no you couldn't put straw back in, the point of the bale is an object like a stone or boulder you can get stuff out of, for grabbing bulk straw. If you've ever worked with a bale of hay before in real life, you'd know it is nigh impossible without undoing and redoing the bale entirely to get straw to go in and stick, at least if you want the straw to stay in any form of usable condition (you could crumple it up and shove it in but hten you just have lots of shredded broken straw and that's useless in real construction other than as bed filler-- crappy bed I might add... maybe as animal feed or as hay for, well, cleaning up excrement).
EDIT: I can also see making the quality average out, after all as you pull straw out of the bale, you couldn't guarantee getting all the same quality, it'd just be a bundled handful, so yeah, make it average if that's how they work it.
EDIT2: I read over the linked comments, I ESPECIALLY liked: viewtopic.php?f=5&t=13582&start=10#p152796
And the fact that, if this is a bale made by hand, likely it only has so many straw units - most commercial hay balers are baling straw by quantities we couldn't even remotely handle, but 25 units baled together? It'd be liftable, only with the string tied but it is liftable. I like, however, the idea of 10 string for it, because a lot of string is needed to hold straw together.