I think you are confusing engineering with design. It was one of the worst engineered consoles, as evidenced by the enormous failure rate. But it was a well designed console conceptually.
However I think the conceptual idea of having a small pool of super-fast RAM isn't the best or ideal design approach. Because to get the best out of a console you need to figure out how to use that small but fast RAM pool to optimal effect. Having a single unified RAM pool is better for developers IMO. PS3 made life difficult by having separate RAM, but PS4 got it exactly right by having a single pool of fast RAM. From the perspective of design influence that super-fast RAM concept has been rejected by the technically superior 8th gen console, which also happens to have the most efficiently engineered unit, and a compact form factor, as well as being the sales leader by a wide margin.
TBH I think that even though developers had a hard time with the Cell, by the end of the generation 3rd parties had got the hang of it and Sony could have made PS4 based around the Cell 2.0. But I think that was ditched because Sony and IBM more than likely hoped The Cell would be adopted into hardware beyond PS3 and when that didn't happen they probably decided not to try to keep pushing The Cell concept. But continuing with that architecture into the 8th gen could have reaped considerable benefits, including full backwards compatibility with PS3. Though perhaps a $399 launch price might not have been on the cards.
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