Apart from the lack HDMI and the low build quality which caused RROD I think the specs of Xbox 360 were ideal for the time. It's still going strong after 8+ years on the market and has cut the PlayStation market share quite a lot is a testament to that.
The PS3 specs to me were a mistake. Having a less straightforward but more expensive/powerful architecture in the cell over a cheaper but more straightforward Xbox 360 PC like architecture was a bit of miscalculation. Especially with PC style games are now dominating PS3/360 sales. Including Blu-Ray was the other the big issue. Larger physical media sizes are still not even that essential these days and I am dubious that HD-DVD competitor was ever threat to Blu-Ray that they need the extra Blu-Ray player user base by including it in the PS3 to win.







