Nothing here about tassels being *too*long; rather, it is merely a simple statement of fact—i.e.: an honest observation:
Matthew 23:5
5 But they do all their deeds to be noticed by men; for they broaden their phylacteries and lengthen the tassels of their garments.
“Broaden” and “Lengthen” imply that there is a standard. Who / what / where is the standard?