exactly, the problem is that after "nailing down the core gameplay early" the gameplay loop doesn't change at all. get signals, get hashcodes, send everything, repeat. The only change in this loop is that you gain the ability to upgrade signals, but it's just another computer that you insert disk into and it does stuff.
p.s: "need to step away from the game for a bit in order to refresh your experience" i played for ~1 week after release of 0.6.3, 0.7 and 0.8, "burning out" is not the case