So... if you rewrite the rules, or use variant rules, or use them to shore up unoptimized builds, then the boots doesn't suck as bad.
Got it.
Or, this could just be how someone else reads the rules, not "homebrew level" variant rules. Anybody who is not too stingy with their interpretation of all those move-then-act rules in between the abstractions of rounds and such already allows the boots to be useful and fun, simply by assuming the movement in the previous round counts as running start, for instance. I don't even see this as contradicting anything Crawford tweeted.
They are a nice addition for a 'burglar' type in an 'burg' environment (which reminds me rogues actually can "cunning action" the boots up), for an armored guy that likes to surprise enemies with their unexpected mobility, or to the small-race member of the party.
I myself really enjoy these kinds of magic items, as I feel I can reward the heroes with nice toys even at very low levels without jeopardizing the expected challenge they are facing.