Good points, everyone!
It's not really a matter of openmindedness, BfSqĀit's really more about how much data you can process at once. Aesop's fable about the hedgehog and the foxĀthe point of which is that the fox knows many tricks but in the heat of the moment can't decide what to do, while the hedgehog's one trick always works and keeps him safeĀis relevant here. A limited tool set that you hone and practice to keep razor-sharp, and which meets the spectrum of street attacks that are (according to people who study the statistics of such things) pretty restricted in number, is going to stand you in better stead than a large number of techs that are all fighting for space in muscle memory.
It's also true that if you study the great TMAs in depth, you'll find ranges of technical tools that aren't generally taught or recognized. The grappling (i.e., close contact controlling) moves of Karate and TKD have begun to get new attention as a result of people studying their histories and taking seriously the contribution of the pre-existing grappling styles that fed into them (Simon O'Neil's book has a nice argument about the contribution of Yudo to the technique set that the Kwan founder would have been exposed to, along with the karate they learned in JapanĀwhose jiujutsu background has been explored in data brought to light by a new generation of karateka). My own feeling is, the place you really need to be open-minded is in connection with your base art: look at it in a fresh way and you may find skill sets latent in it that you didn't realize were there.