Weird how casually we drop the 5th interval on dominant 7th chords

Something I've noticed recently, after years of playing ukulele, is how casually we dispense with notes in chords when we don't necessarily have to.

I pay enough attention to chord construction (1, 3, 5, b7, 9, etc.) that I can usually work out unfamiliar chords from a lead sheet. Because the uke only has four strings, and because of reentrant tuning, compromises are inevitable. Once you get into 9ths, 11ths, and 13ths, you have more chord tones than strings, so notes have to go. Usually the root and/or fifth gets sacrificed.

What surprises me is that the same thing often happens with dominant 7ths, even though a dominant 7th only has four notes and we have four strings.

For example:

• D7: 2223 contains all four notes (D, F#, A, C), but the common "Hawaiian D7" (2020) drops the fifth and doubles the b7.
• F7: 2313 contains all four notes, but many players use 2310, which drops the fifth.
• Christopher Davis-Shannon recently suggested 3003 as a nice C7 voicing. Again, it drops the fifth and doubles another chord tone.

In all three cases, the omitted note is the fifth.

My understanding is that the third and flatted seventh are the critical notes because together they define the dominant function (the tritone). The fifth contributes comparatively little, so it's the first note to get sacrificed.

If that's correct, why did these three-note dominant 7th voicings become so common in ukulele tradition when four-note alternatives are available? Is it purely a playability issue, or is there actually something people prefer about the sound of these incomplete voicings?