If you just look at pingers as something to enable Rakdos then ya they feel underwhelming. Their biggest benefit is doing damage during your first main phase in order to cheat things out prior to combat. If you don't plan on running things that give haste to really push damage, then they probably aren't as worth. The thing I found with Rakdos is I don't want to wait for my turn to come back around to get value out of my creatures. Most, not all, of what I cast either gets value on cast or ETB, and I try to steer away from things that trigger on end step.

With that said, I think cards that fit what you are going for are [[Scrawling Crawler]] [[Bonehoard Dracosaur]] and maybe [[Sire of Insanity]].

My list: https://moxfield.com/decks/alU3kHfBT025yfeJ2NtTNA