Yes we should use it because it's better but the practicality? There's so much gear that's HDMI that would have to be replaced or require new active adaptors. It's so much industry and consumer effort for such a marginal gain.
- HDMI v1.0 initial release = 2002-12-09
- DisplayPort v1.0 initial release = 2006-05-01
To be sure, just under 3.5 years; HDMI rolled into v1.3 a month after DisplayPort v1.0 saw the light of day. Agreed on the impact of market inertia.
For every computer monitor there are hundreds if not probably thousands of televisions.
HDMI's marketshare has everything to do with who the players involved are and just how much weight they have to throw around. Even computer hardware generally have more HDMI ports than DisplayPort ports.
DisplayPort never could have replaced HDMI because DisplayPort never tried to solve the same problems HDMI did.