Please see #5.
The current way of doing it may seem inaccurate, but it’s certainly a lot simpler than trying to guess the value that the deceased added to the inherited possessions.
I have a background in real estate investing, and I could work around those challenges without much effort at all.
If the proposed capital gains "reset" tax is imposed, you'd simply have a huge incentive for Grandma to sell the house BEFORE she dies -- maybe even to family members at a steeply discounted price. Voila! -- you've eliminated any concerns about improvements dating back decades and reset the value for future capital gains tax purposes in one fell swoop.