Probably logistics. They had hacked the smartphones, so Hezbollah decided that they would turn to older tech that was harder to hack or intercept. But of course this presented a great opportunity, as there aren’t that many maker of pagers left in the world. So the Mossad probably interdicted the delivery process to tamper with them and insert explosives.
Lithium batteries don’t explode, they fizz really quickly into a flame. The incidents reported included an explosion, and in several occasions they injured not just the user but several people around them. EDIT: apparently they didn’t even have Lithium batteries, just use regular alkalines. So there was no way to make them explode without inserting an explosive and rewiring the device. Alkalines also just tend to leak when they overheat, not explode. To make them explode you have to feed them with high current, which the pager doesn’t have space or circuitry inside to induce that, and it is still very rare even when you do overcharge them.
I was thinking the same thing. This isn’t your Nokia IED where you just wire the ringer to the detonator. There must be some additional circuitry to handle a special signal. A pre-programmed high-pitched ring for certain numbers maybe? Or a little logic chip to recognize numbers or messages?
