Really the more important point to note is that pooling for variance reduction has absolutely nothing to do with delegating control. Running a outbound only bitcoin full node, past initial syncup uses less than 20kbit/sec bandwith and a fraction of a percent of cpu... it's not costly to do, purposefully so.
It's perfectly possible to individually run your own consensus decisions but agree with others to, in a provable way, pool your payments. This is what P2Pool does.
Unfortunately many Bitcoin miners don't have a rigorous mathematical understanding of how mining works— they erroneously believe it to be a race where the fastest wins disproportionally— something entirely untrue (absent some proposed attacks which are not happening in practice)... just keeping yourself from getting scammed by the many scammy hardware companies is basically a full time job itself. Then you have various technically unsophisticated Bitcoin pundits claiming that hashpower consolidations in pools isn't something to worry about... not a great mix.
Fortunately, the reasons for the current behavior are mostly inertia— if P2Pool had been invented first the symmetry would have broken differently. It's still possible that there might be a massive swing (say if GHash.io decides to steal a bunch of coins from their miners and makes a runner).