One little hint to get your facts straight:
New skarner has also a total ad ratio as physical damage on the ult, adding 120% ad total which is ~170 at lvl 18 just from basestats.
Also for the comparsion with nauti, his raw base as+ad and the spamabillity of his Q still give Skarner more dps than naut, even autside his crystals. just that dpsing as a immobile melee is not a very realistic scenario and compared to similar champs like udyr or mundo, his damage is nealry non existance.
Notsaying skrner doesn't need love or work(i personally would love a revert to his OG state, or a mix from the OG and first rework, i really miss his old healing mechanic), but i still think we should stick to facts when discussing him.
However, i think the ult doing low damage is totaly fine, else it would once again consume to much of his powerbudget.
my main issue with current scarners damage is that his Q feels meh and 'charge' mechanic feels pointless without the old stacking buff or the very old slow and that his AS sucks outside of the crystal zones.
Other than that, i really miss meaningfull AP ratios and more magic damage. Beeing hybrid both in damage and scaleing once was scarners thing, now his E and ult do half physical damage shifting his overall damage profile alot more towars physical, and his Ap ratios went from greate on his OG state, to ok in the first rework to barly any on the live version.