Cartridges actually have much faster load times than discs. Notice how the Switch has reverted back to cartridges? They’re faster.
As for the controller… It is pretty odd. Though, at the time, we didn’t have the same standard for controller design we have now. So it makes sense that Nintendo would try something bold. Then after they had committed to the design, the world decided the PS1 controller made much more sense, and that became the benchmark for future controller designs.