Exit stage right: As Nepster says, solution still works but second floater is not needed.
Need a Boost?: My solution is completely different, and still works. I group the crowd in a pit on the bottom level, using one walker to stop the digger and another to stop a second digger to release them. With the change, the second released digger separates from the crowd, but this is easily fixed by using one of the spare walkers.
Segmentation Fault: My solution is unaffected. One walker is used to cancel a platformer (this lix dies anyway), one to cancel a digger (this lix would still exit).
To Destroy is to Construct: Backroute exists regardless of walker behaviour, and can be fixed with a terrain change.
Trapeze of Weird Blue Blocks: Becomes simpler because the freed blocker can exit without needing other skills. A pity, as this is an interesting part of the puzzle.
Survival of the Craftiest: My solution is unaffected. As this is an anything-goes level, I'm not concerned about alternative solutions.
3.1.1.1: My solution is unaffected. (I use jumpers to cancel diggers on the thin vertical strips.)
Finale: My solution is unaffected. Nepster said later his supposed backroute doesn't work.
Path of Wickedness: Same as above.
Seven Pillars of Lixdom: Solution is unaffected. The replay breaks because the freed blocker was assigned a skill later, but this could have been assigned to any other lix.
The Circular Ruins: My solution uses a walker to cancel a digger. However, there is a spare walker to turn her round again.
With that out of the way, time for general thoughts. I don't feel very strongly either way about this change. The point about making the skill state-free, and therefore easier to explain to new players, is a good one.
I've always liked the walker skill, because it has the different uses of turning a lix, or cancelling a skill (including blocker), and since you don't know in advance which will be required by a level, this makes for interesting resource-management decisions. This would still be the case after this change. There are some situations where the walker becomes more useful because cancelling a skill
and making it turn is exactly what you want; there are some where it's less useful because you want the opposite. Either way, you can fix the problem by applying a second walker. After the change, where cancelling and continuing in the same direction is the more expensive of the two, you can alternatively cancel (anything other than a blocker) with a jumper or batter instead.
The old walker feels more natural to me, because I can see how it might have arisen in the design of Lemmings 3: supposing it was first created as a skill that cancels other skills and makes the lemming walk again, the designers asked "What if it's applied to a lemming who is already walking?" and came up with the current behaviour. Also, with the old behaviour, cancelling with a walker, jumper or batter are all consistent with each other. However, if you changed the icon as suggested and renamed it "turner", the behaviour of always cancelling and turning would feel natural too.
So if it came to a vote, I'd vote for keeping the old behaviour, but I don't feel strongly about it and think you should go ahead with the change if it's definitely what you prefer.