First off "try" is a key word because they aren't really succeeding on that front. Also even if they did, those are still their original shows so it'd make sense they'd try to reach for that similar tone. Not so much Ren and Stimpy since as others have pointed out, it's quite different in tones.
But yeah this isn't going to happen for a variety of reasons. Ren and Stimpy not being relevant for now over a decade, their last attempt being universally loathed and not even suited for children, Nickelodeon having no interest in reviving any of their own old series much less ones that jumped network, and so on and on. Also even if all of that wasn't true and for some reason Butch Hartman's team wanted to do more Ren and Stimpy (something they've never shown an interest or talked about so it seems honestly random to bring them up as the ones who'd do it) Nick still wouldn't air. Really even though FOP is still going on Nick that's mostly because of it sort of establshing itself on a franchise level below Spongebob, but that hasn't stopped Hartman's other works from finding that level of success. Both Tuff Puppy and Danny Phantom were cut down without a terrible load of fanfare which implies to me Nick really interested in more of Hartman's work that isn't the original. So they wouldn't be interested in this so again... feels rather pointless to speculate about it honestly.
Man now I"m up to 7,000+ posts. Hard to believe it took me 8 something years to get that many. How long will it take me to get another thousand? Guess you're going to have to keep reading what I have to say to find out.... I hope you've been doing that anyway as I feed off the attention.