@Riot Let's talk Wall of Pain

It's become quite apparent by now, that many of the champions coming out have mobility. This isn't normally a problem because hard cc is the counterplay to mobility; however, soft cc (aka slows) are much weaker than their stronger counterpart. This is to be expected, but slows are practically negated by mobility. Moreover, a few champions, namely , have exceptionally weak slows because they diminish in potency over time. slow is relatively compensated for the fact that it has a relatively short cooldown. Unfortunately, wall of pain is a completely different matter. Have you noticed that WoP is in an incredibly bad spot, not just in the meta but also from a design perspective?

For anyone who doesn't know, let me start off by describing what wall of pain does:

Karthus creates a wall at the target location for 5 seconds. For the duration, the wall grants sight around it, and units who cross it are both slowed (reduced by 50% after 1 second and decaying over 4) and lose 15% magic resistance for yet the same duration.

At max rank, WoP applies an initial 80% slow which drops to 40% after 1 second and continues to drop further over the remaining duration. There are several reasons why I think this is severely crippling to the ability:

1. Rank 1 WoP applies an initial 40% slow which decays over time. Basically, max rank WoP is simply a rank 1 skill after 1 second.
2. It has an 18 second cooldown for what seems like a lackluster ability.
3. 15% magic resist reduction is incredibly lackluster against anyone not having over 120ish MR.
4. While the wall does cover a huge width, the actual area is small and the placement is fixed (what I mean by fixed is that you can't position it to your liking such as rumble ult or viktor e, depending instead on the direction karthus is facing).
5. Even when the wall successfully hits, the great majority of times it feels like it does next to nothing because of reason 1 and the amount of mobility in the game. It's even more useless when the opponent has tenacity or slow resist.

Do you feel any of these issues are substantiated enough to consider reworking the ability or buffing it? I feel there are other issues with Karthus' viability in this meta, but this ability in particular not only feels underwhelming but also outdated. I welcome anyone who would like to discuss this ability and hopefully bring this to Riot's attention.