I addition to everything Tonys said (including the net height stuff), I would like to add another way to look at the "half of the clubs" analogy with golf. If, like nearly all good defenders, you use a markedly different rubber on one side -- typically long pips on the backhand -- you have effectively given up 99% of offensive capability on that entire side of your body. In effect THAT is giving up half of your clubs.
For the last 50 years or more, defenders have always been in the minority among top players. In fact, from a game-theory perspective, a lot of the success a few of those players do have DEPENDS on their being a minority strategy. There has not been even a single defender who has won a grand slam tournament in the 1970s, 1980s, 1990s, 2000s, or current decade. In fact, only one has even reached a final. The number of defenders in the world top 50 has stayed constant throughout this entire period. A handful can be effective because most players don't get a chance to play them very often and so don't know how to play them correctly. From this, at the top levels, one can clearly say that playing defense is over-rated. And in table tennis we don't have the equivalent of a Roland Garros Stadium with a super slow surface where a defensive style can be optimal. They are always fun to watch, though.
Golf if always a very bad analogy for the vast majority of what happens in table tennis.
If you're close to the table, also, you just don't have time to twiddle much. Actually, the best twiddlers I have seen outside Akerstrom and Filius are a handful of LP penholders playing in women's game.