It's probably just that replacing too many parts when one breaks was getting too costly for them

Maybe I'm reading too much into it, but adding convenient pull tabs really does feel like a shift in direction to at least be less hostile to non-Apple or DIY replacements. They could have easily opted for a special battery removal tool.

What good are pull tabs when you cant buy original replacement battery(1)?

/1 without giving up your business books for 5 years selling your customers privacy, and giving up ability to do component level repair.

More good than not having available replacement batteries and also having the original glued to the case?

You know, it could be both...