There are so many great replies in this thread!
First, I want to say that I understand the inquiry of the OP. I also had occasions when Aces seemed to be a promising potential, which never manifested (on some occasions). For example, when I just started Tarot, my friend asked me her chances of getting a new job (she was a grad student back then and wanted to work in a medical clinic, as an assistant to welcome patient and orient them in the hospital). So I got the Ace of wands as her ''chances to land the job''. Turns out that she hated her prospective boss and she was not proactive at all, so you can guess that she did not get the position. With a better grasp of Tarot now, I can understand why we got the Ace of WANDS and not any other Aces (like the Ace of pentacles). It is because she had to act right now to get this job, but was instead very passive, so the fire here (opportunity) was extinguished.
Personally, I think that Aces are as ''powerful'' as higher cards in the suit. The main difference (beside the ''potential/seed'' aspect of Aces) compared to other cards in the deck,is that Aces are a RAW and DIFFUSE energy (i.e. a scattered energy). For example, Ace of wands, as a sexual energy, is a primitive form of sexual attraction that can come suddenly and be more difficult to master, compared let's say to a king of wands energy.
I think that everyone is very accurate when saying that we have to make effort and work on the potential of Aces to make something happen. However, sometimes this potential is not under our control and hence, the opportunity can also disappear despite someone putting a considerable amount of effort.
So to sum up, when seeing an Ace as a ''potential'', I think that more than often, other cards should support your demand to make your project come true.