I don't think that's fair. The site of ooc was chosen because of the connectivity potential with the biggest being with the great western which is being built. They're building the passive provision for any Chiltern connection including ensuring the new bridge over OOC Lane is big enough.
The site is constrained as to where the hs2/gw station can be put, there's no passive provision required for LO and building the stations there as part of hs2 would have only added to the budget, then used against it, especially with nonsense cost per mile comparisons.
Perhaps if OOC had been built as a separate project under a different budget to the line, more like how they might do it in Europe, then it might have had a slightly different approach with the LO stations, but its an essential part of hs2 that is difficult to split off.