The dewy eyed lamenting of the passing of Starwood is unhelpful in getting to the heart of actual issues so is likely to drive a lack of response as there is nothing that can make you feel better about that. Whether Westin is better or not that MVC, or any other brand, is irrelevant when the footprint of Westin resorts is so limited for many MVC owners. If you are feeling dismissed, it is probably because in a much larger owner pool, your concerns don't resonate with the majority. Similarly if you are a non-US owner MVC you will find much of the chatter and drive around MVC, very US centric and you can choose to label that as being dismissed. There are many sub-populations within the overall owner pool so Westin owners are just another one of those.
MVC IT has never been great, and many MVC owners fight strong and persistently to improve it as experience is that venting continuously doesn't work.
As a VAC shareholder, you should also understand that MVC did not take over Vistana, but the parent company of MVC, MVW bought them as part of the ILG acquisition, and, thankfully, the brands remain separate other than the ability to use the Abound Exchange across them, as they can also use II. If you are focussing your criticism at MVC, its likely that it is misdirected, so best you target the correct source to get things resolved. Its quite normal in Corporate politics for smaller entities to struggle with interaction with the mothership and blame them, or their larger cousins, for everything, when they actually have a good deal of ability to make the best/better of where they find themselves and just don't. Within the MVC portfolio there are resorts that are excellent, particularly in the Far east and Europe is good too, so its not the MVC brand that is causing the problem if Westin resorts are declining, something else is driving it.
Yes they caused confusion by having the grouping called Marriott Vacation Clubs, note the additional s on the end, thus enabling people to get muddled that the MVC timeshare brand was somehow getting involved with Sheraton and Westin, which is best avoided. Sad they couldn't come up with a better name.