It's very convenient to be able to fry 40 hashes or test tube 250 compounds. The beaker needs some love too -- the one-at-a-time design is fine if you're making ESHP, but for any of the cheaper powders it's a pain in the ass.
Besides, it's not like there's some massive gameplay difference from sitting around to constantly re-click "Make more [Powder]" and "Make" repeatedly.