There’s a lot here, and for good reason. On their own, fourths are pretty useful. They work great as double stops, they’re inverted fifths from the top note, the ♯4/ ♯11 is the heart of Lydian & shares the same address as the blue note, and they’re almost always easy to play. Something I’ve only recently learned (from Truefire’s Interval Insights) is how many great approaches and departures there are from fourths. Hammers up to the major 2nd, up from the major third, and even up to the fifth or from the minor third all sound great from the perfect fourth. I’ve yet to experiment much with the ♯4 and it’s neighbors, but my sense is the 5th provides a nice resolution.
Hammering the root up to the second creates a nice minor third of its own and also provides the top two thirds of a C-shape triad on the lower string if you bring your pinky into the mix. You can’t help but hear Hendrix with this lick.