There are reasonable ways to approach it, I do think a number of options per X number of points would be best but not absolutely necessary. It needs to be restrictive to be effective. Any change that's for the overall good will have winners and losers. I think 2 or 3 per UY for most any owners would be more than fair. I guess it depends on how we define large point holders as well. IMO the bottom line is you want people to not be able to change existing reservations easily or without serious consideration, limits holding days one likely won't use and you want a system that does not encourage multiple phone calls when otherwise unnecessary. As
DVC has proven a number of times, when you try to nibble and cut out just the extreme's, it doesn't work well and tends to cause other issues. A single solution that's easily workable within a computer system that does all of these things would be best. Any time you try to define extreme as "more than what I do" and protect the options one uses, it's going to be a poor system almost 100% of the time but even the best option won't be perfect. I'll say again, it needs to be painful and make people really think about it and only change if absolutely necessary. I'm sure there are a few of ways to approach it. Another would be that you can subtract but you can't add to a given reservation and you can't combine reservations. Personally for me, walking should not be allowed related to the reasons I've just stated and it needs a cold and simple fix, not a complicated computer algorithm with essentially little or no if/then type of options. Such a change will be negative to some, no way around it. This could be handled as part of a VIP program as well which would almost certainly be related to qualified points only and should address your thoughts on having sufficient options to handle life without encouraging walking or holding reservations.
The reality is that walking also has a real cost in terms of $$$. In that sense it's a little lot the valet parking issue where a subset are increasing the costs of the group. In that sense, pay to play may be the most fair. An no, it's not like the issue of a pool or exercise room at a resort that a given member might not use it is much more like the valet parking change.