While I don't want to be another killjoy thread, increasing the duration of dots to 20 seconds seems like it would cause longer downtime of inactivity rather than making it more combat friendly. Other MMOs don't have this problem when you have a large action bar of over 2 dozen attack spells, utility buffs, and defensives at your disposal. My Feral Druid has well over 20 buttons on WoW that I actively use and manage multiple Bleed attacks in the process. However ESO limits you to 10 total lets say 2 are utility buffs, 1 heal and/or a defensive, that leaves you with 6-7 attack spells at most. Once you cast all your spells, you don't want to overwrite them before they finish thus clipping the damage, but you'll probably be using Light Attacks and a burst spam ability more often not less to fill in the time spent not having to refresh, exasperating the problem further.
I really enjoy the set Diamond's Victory on my magicka build characters, there's a tightness in durations and alternating between ranged and melee abilities that feels smooth enough that I can power up my attacks and refresh my dots that I'm not clipping them but also doing it in a timed procedure. The only character I have that comes close to Light Attack Weaving is a Templar with Molag Kena, High Isle, and Diamond's Victory. I alternate with casting Reflective Light, Solar Barrage, Degeneration, then Puncturing Sweeps with Light Attacks thrown in after each sweep, double light taps for Molag Kena procs. If the other buffs from my sets aren't also brought up the same way I feel like I will end up having to clip my dots for Melee Supremacy more often, not just the Templar but on all my magicka build characters as well.