I don't have any experience with steering assemblies on the Original or earlier version Cubs but have worked on quite a few of the Wide frame steering assemblies and would have to disagree with you on it being a weak point. Most of them have been abused for the last 20 to 30 years and are still working with a little slop and some grease on them. There probably isn't a single lawn tractor at Lowe's or Sears that will probably be running with a steering assembly as tight as the Cubs in 10 years. There are a couple of problems but they are easily fixed.

When I clean the 30 year old grease out of them I normally find the shaft and bearings in good condition.

Quite often I find the side plate warped, probably when they welded the bolt on it at the factory.

 Put a straight edge on it to check and straighten in a press till it is straight.

Replace the cam follower or sometimes I redress it by putting it in my drill press and use a file and
emery cloth to reshape it.

When I reassemble it I put on a new gasket and attach the side plate with a washer,
 a thrust bearing (Nice605}, washer, and a lock nut. Adjust the lock nut until the gasket starts to compress.

 (I got that thrust bearing idea from Donald Mayes and it has made the steering much easier to adjust and improves handling). This isn't power steering but it ain't bad....

Some additional comments on Cub steering repair. I was posting late last night and this morning I thought of a few more suggestions for someone who is doing a steering repair for the first time. I tried to follow the Service manual and adjust the steering assembly while on the tractor. Just wouldn't work, the more I adjusted the worse it got. You need to remove it to do it right. It is easy to remove if you don't have the hydraulic controls mounted on the steering column. That's why I always recommend rebuilding your steering assembly if you have the engine removed.

Get all of the old grease out and be careful not to lose any of the ball bearings as they will pop out of the plastic holder, if they do just put them back in.

Check for any pits on the steering shaft that might wear on the cam. Use a file and emery cloth to dress it up.

If you get your side plate straight it should get good adjustment over the range and the grease seal will make better contact. If you look at the picture of the side plate I posted you can see the paint isn't worn even indicating the seal wasn't touching at the ends of travel.

When you put it back together follow the manual and make the adjustments on the bench.

If you use the thrust bearing you cannot use the two nuts so you need to get one lock nut.

Leave the cam adjustment loose while you tighten the lock nut until the seal starts to compress. Then adjust the cam while rotating the steering from one side to the other. It is not perfect so you need to adjust for the best from one limit to the other.
Again I would like to say that I got the Thrust bearing idea from Donald Mayes and so far it has worked good.