You can enjoy both, but sometimes, and mainly due to lack of extra hours on the clock. The focus needs to be maintained on often divergent set of problems.

Not all programmers are very familiar with hardware issues, or dependent on their area of programming expertise on network design.

I also found that many programmers are oriented towards creating new features, while administrators focus on running established tools at maximum efficiency.

While drawing on the same set of qualities, the interpretation of them can diverge.

Some people posses both sensibilities and the mind space to treat both disciplines well in environments and projects that scale. They are not common.

maximum efficiency, bah! a good sysadmin is focused on keeping shit from breaking. If that means putting up an active-active redundant system where you really only need the capacity of one system, so be it.

Those of us who get paged when the shit hits the fan tend to be pretty careful of breaking things; and quite often, we work on systems where relatively short downtimes can lead to losses greater than our yearly salaries.

That said, all the best SysAdmins have at least some background in C and NIX systems programming, and nearly all NIX systems programmers are also pretty good SysAdmins.

And these qualities make sense in consulting and many other domains, too. So would you let a consultant run your servers then? (I know this is a bit over the edge, but...)