I'm talking about the field as a whole. Quads back then were necessary to win. Now, they're necessary to place in the top 5. Men are making more mistakes this season, but still getting scores as high as the 2010 Olympics, because they're increasing their overall difficulty.
I agree that the jump standard was high in 98 and 02, but the overall difficulty of the programs was not nearly as high. If you took the overall field and their capability of doing a quad, there are far more skaters who can land them today (which is expected).
At the 1998 Olympics, Kulik was the only one with a mastery of the quad. Stojko was his main challenger, but had minor errors and his injury of course. Though they could all land 3As, the quad was still pretty elusive to the rest of the field and as such they weren't nearly up to par to Kulik let alone today's skaters.
At the 2002 Olympics, Plushenko/Yagudin were the strongest of the field by far, and the rest of the field was totally watered down other than Goebel - a consistent quad technician with a lack of artistry, and Honda who was a Takahashi-type in that he had the potential to beat Plushenko/Yagudin, but needed a clean skate and errors from the top 2. The rest of the field wasn't really quad technicians but there were some solid skates. Jumps-wise, this was probably the best Olympic field to-date.
At the 2006 Olympics, in the SP, only 5 men of the field landed quads. In the FS, of the top 8 men overall, only Plushenko landed a quad. Along with the 2010 Olympics, there were tons of errors, likely attributed to higher difficulty post-CoP. But the level of skating and other elements (spins, footwork) was wayyy higher than before, thanks to CoP.