Midiclorians sucked because they were an attempt to explain something supposedly inexplicable. The Force in Star Wars is supposed to be some all encompassing transcendental element of the human soul, a universalist web of fate which can be manipulated by those attuned to it. Midiclorians sucked because they tried to pinpoint its source in biology, and they sucked harder because after one mention, Lucas dropped them from further outings in SWII & SWIII, which made them seem even more invalid and unimportant.
Define "explain". In KOTOR2, Kreia offers her own explanation of the Force which is quite popular here on the Codex.
There can be good explanations and bad, banal, uninteresting explanations.
And is Kreia's explanation considered canon? Kreia's explanation was qualitative, not quantitative. You cannot compare hers to Qui-Gon-Faggot's.
The explanation offered by Kreia was a philosophical one, and it was written because of Avellone's distaste/disgust with the Star Wars universe. It is a deconstruction of the force and the emptiness of "The Force" as a signifier. The idea being that if the force is alive, that it ca die. That if it is all encompassing then it can also be all consuming. That if it can fill an individual like a vessel, than an individual can be emptied or voided of it. MCA explored the
plot holes and loose ends of the force and didn't seek to explain them empirically, but to highlight the fact that they are exactly that: plot holes.
The midiclorians was an attempt to empirically categorise The Force as a material/biological element of the universe, which manifested as some kind of quantifiable organism inhabiting specific individuals, the proliferation of which resulted in said individual being attuned to "The Force". The fact midicilorians were a shit explanation was because it was an attempt to explain the existence of the Force, which was incredibly disconnected from the actual presence of the Force in the Universe and its use by the inhabitants of that Universe. How can the Force be the web of fate, as well as a "super power" but it comes about by micro-organism. That made even less sense than leaving the force unexplained.
Kreia never
explains the Force. She gives the player an insight into what Avellone understands the Force to be and what the Force is not. She also
follows to their logical conclusions every descriptive term applied to the Force in the original film trilogy and some of the expanded universe. There is a difference between qualitative explanation and quantitative.
Kreia is the former, midiclorians are the latter. The Force, as it exists in the Universe is unquantifiable. Lucas attempted to change that and failed. It was not a poor explanation it was an unnecessary explanation and a completely ignorant attempt to bypass the Universe he constructed, by disconnecting one of its major elements from its own function.
Edit: Just to clarify: The reason Kreia's "explanation" (lolherpderp) is interesting and even compelling is because it raises more questions than it answers about The Force. As would any philosophical analysis of some transcendental universal power, lol hai hegel.