Currently, we are stuck with PM Abiy for everything and we can't change him until the next election. That is too long. Even then we are not sure if the inept opposition can become mature by then and if not we are stuck for yet another five years with the same PM. Hence the current system makes it very hard to introduce change of the PM from inside. The presidential system on the contrary helps the ruling party to react quickly and replace low performing prime ministers without waiting until a push comes from either the opposition or the people.
PM Abiy is good in some areas like ICT, rebuilding the military and security, focus on agriculture, having vision etc. but he is greatly lacking in many practical economic areas which is resulting in an increasingly frustrated population. As the Americans say, it is the economy stupid! If a government fails on the economic sector then it is surly doomed!
I suggest PM Abiy should introduce a presidential system, become the president, appoint a competent PM and focus on what he is good at. I suggest he should appoint the CEO of Ethio Telecom Frehiwot Tamiru to be the prime minister.