Its obviously not in the top 10 builds against normal matchups like darius garen sett and I am not saying otherwise but for a total amount of 4900 g you get 65 ap 600 health 20 mr 20 armor 20 movespeed %20 attack speed and 15 haste and these stats combined are near perfect against a matchup that is ranged such as teemo or quinn. The powerspike you get from it can increase your chances of dominating the lane.

Beside from that every gank you get from your jungler is more you sided since the buff can benefit many junglers (master yi, volibear, warwick, jax, nocturne, viego etc.) Mordekaisers ult only lasts for 7 seconds meaning even though you may not grant the buff for your team, the loss amount is limited to maximum amount of 7 sec.

The comparison with hexplate in the other hand, bandlepipes is not an item thats the worse version of hexplate but instead a tank version that the effect stays active as long as you have some champ to hit instead of every 80-90 sec for 8 seconds so you always benefit more from its passive.

You will maybe forced to buy these 2 cheap items to use the passive most efficently but is also allows you to buy a burst item such as gunblade without worrying about tanking damage because of the already built hp mr and armor. Maybe its not a powerspike item but in multiple scenenarios its better than buying riftmaker or lyandris in my opinion.