So how much will you have to "re-deploy" after you pay taxes on all those profits. Keep in mind those wonderful almost tax free distributions have to considered and some recaptured. I own 3 of the companies you mentioned and I really like them, but not as much as KMP.
First of all P/E is not a valid metric on which to value MLPs. Due to pipeline depreciation, they could run at an astronomical P/E pretty much indefinitely, indeed have been for decades. The valuation needs to be based on DCF.
Apart from that, this poster is right on about the tax consideration. Let's say you have a $20k position yielding 6%. You sell and pay $5k in taxes (quite possible if you've been holding a while). You now have $15k to reinvest. What yield do you need to get the same level of distribution income? You need 8% yield to get the same level of income, meaning you need to move to something with higher risk. (This example is in general terms, not saying anything specific about KMP).
Thus every time you sell an MLP you've had for a reasonable period and reinvest elsewhere, you will have to either accept lower portfolio income or accept higher risk. Once you've held for a few years, it's generally better not to sell unless something materially changes the company prospects.