Both of these have already been covered. To recap: destroying the heart had no effect on anything because its a gameplay thing.
Is this actually said by credible source or is it your personal thought about it?
Do you want them to have scripted all Dwemer critters to suddenly die at the end of the main quest? That would have made Dwemer dungeon diving boring.
Sure, but it would've made sense. Even if it was lazyness or gameplay aspect I also didn't recall hearing dwemer stuff powering down from Oblivion rumors.
To be honest it would've been pretty cool to see powered down robots all around the dungeons and have other critters spawn there instead when the robots weren't guarding the ruins anymore.
The Dwemer ruins in Hammerfell/Skyrim function on an different power source, like steam (the Stros M'kai ruins had more steam pipes, iirc).
I recall seeing many pipes reaching down into the lava in Morrowind as well and many steam powered gadgets. It's level designing though.
To me this all sounds like big argument to use Occam's razor on. If they run and can run without the heart the heart isn't needed, we can disregard the heart and focus on what really is powering the heart. This is what I would do if the world was real and I was a scientist there trying to figure this thing out.
Its not 100% certain that the Vvardenfell constructs were heart powered, but it makes sense, given their extensive research and use of the heart in other areas (like giant stompy robot gods).
Sure, but if they can run without the heart the heart isn't needed. We do not need that hypothesis.
Chimeri_warrior (misspelled name?) had better hypothesis on the subject. If someone were to go study whether they can transport the robots as far as they could with the heart and they would act the same as in the time when the heart was active the hypothesis that the heart is needed could fully be wiped off the table, considering the heart really is destroyed.