It has been 10 years since Skoda Transportation launched the 15T with 100% low floor as well as pivoting bogies and bogies under articulations. But even now, most new low floor rolling stock still has fixed bogies and short carbody sections.
Because the price is the leading factor when choosing a tram, not the riding qualities or the damage it will do the tracks.
The Škoda 15T, the Bombardier Flexity Swift (Melbourne E) and Alstom's Citadis Dualis have 4 bogies per 30m of tram instead of 3 bogies per 30m of tram. That extra hardware adds to the base cost of the vehicle, and with the price being the leading influencer of vehicle choice, these designs get knocked out early.
Basically, they only get chosen if the operator specifically pays more for a 'low track impact' tram or needs high running speed for 'tram-train' operation. (Which is were Alstom target the Dualis)