Hindsight is wonderful, yes, but the trends (memory, components becoming faster, cheaper) were surely well known at the time. Still, at least Acorn managed to deliver mostly reliable equipment without resorting to the bizarre or exotic hacks that Sinclair and Apple were up to back then.
And it's also great to learn from such business. Do you plan a big project with lots of fancy components to make things work, or do you hold off until off-the-shelf components and better technology make it all much cheaper and more reliable? Ladies and gentlemen, I bring you round X of the Iyonix vs. Omega debate!