I think "design" is overused in this case. Sure some users base their purchase decision on actual design/look of a console, but that's a rarity.

Success is more dictated by 4 main constraints or factors: - Game selection and support - Price point - System performance (including storage) - Innovative-ness or accessibility

Successful consoles typically met at least 3 of the above. For example the Nintendo Switch had very mediocre system performance, but it had great (1st party) game support, priced lower than competing XBox and PS4, and seemed very approachable for all demographics.