I have the same feelings. Technically R-Type is very impressive, colourful and with a lot of action and of varied, interesting content.As much as I think R-Type is a masterpiece I never really enjoyed playing it all that much
So what if I can't complete the 1st level? If not recordings made by others I would never see it at all.
Renagade is easier but still challenging. Just like other good games from Ocean - Robocop, Rainbow Islands, Chase H.Q.
I have a feeling that the programmers in Ocean were from a different league than all the rest. They were doing fast, smooth games. But they didn't care only for framerates and number of sprites on screen. They could take the gamer's perspective, not only coder's perspective. And make easier games that would be enjotyable not only for some master of joystick but for an average joe as well.
Now, after 30 years, we can see that it was the winning trend. Computer games became much easier so stuff like Renegade and Robocop was jsut ahead of its time