As someone who sells film and chemistry online, I can tell you that their moves are not because they're trying to screw the customer, but to save the customer some money. Shipping glass bottles and tins is exceedingly expensive, and prone to getting damaged in transit when shipping from a reseller to somebody at home. Properly packing it so that doesn't happen very quickly costs more than the product you're shipping, and very few people are willing to pay more for shipping than the product that they're buying. XTOL is a perfect case in point. If it was shipped in a glass or metal tin multipack (part A and part B), the actual cost of the product would go up to about ~$15 from its current ~$11.99. The current plastic packaged product weighs ~20 oz. before packing it for shipping it. Go figure how much it'll cost to ship a 20 oz product in a padded mailer coast to coast. Now, go price out the cost of a sturdy box that won't crush and break whatever is inside it when it has a bunch of other heavy boxes stacked on top of it, then figure what it'll cost to ship that coast to coast.
With the current packaging, a padded mailer costs about $0.50, and shipping 20-24 oz. coast to coast is about $10 bringing your total cost up to ~$22-23. Going to glass or metal tins will easily increase that quite a lot, as boxes typically go via a different shipping method, and sturdy boxes are really expensive, relatively speaking. The padded mailers also have an advantage as they are flexible and rarely sustain damage in transit, even when getting stuffed into a tiny mailbox, which is something you can't do with a box. I can tell you that the cost to box it in an appropriate box and ship it will easily be ~$15 or more.
Are you willing to pay $15+ to ship a product that costs about $15? And to do all that so you can buy it once and have it last longer? The offset in shipping costs alone actually makes it more expensive over just buying it in the plastic package, and just buying another one if it goes bad before you used it. It's one of those false economy things. You think it costs less, and at first blush, logically, it does cost less, until you actually go figure out what it'd actually cost the customer by the time it's in their hands, then you find out that it doesn't actually save the customer any money and has more downsides than upsides. Also, if your shoot volume is so low that you can't finish off a 5 liter package of XTOL before it goes bad, then why are you developing your own film? Certainly not so you can save some money. You're not shooting enough to save money over sending it to a lab.
You see the same thing with 36 vs 24 exposure rolls. Unless you always shoot one emulsion and shoot *a lot*, 36 exposure rolls aren't really worth it because often times you're just blasting off the last handful of frames just so you can finish the roll and go get it developed. Logically, 36 exposure rolls cost less per image than 24 exposure rolls, but how many of those images are throw away because you were just trying to finish the roll? Same principle. Logically, you want 36 exposures for "better economy", but in practice, 18-24 exposures (or less) is about right for a lot of things you'd shoot. Per image it's more expensive, but the total cost is lower because 24 exposure rolls cost less and you can just shoot it and go get it developed without having a significant number of throwaway images that you shot just trying to finish the roll.