Consider:
Yes, MSFT has an interest in selling upgrades and cutting support for old Windows versions, but to the extent they persuade unsophisticated users to move to TPM 2.0 hardware, they're increasing users' security.
And, arguably, the security improvement is worth more to the average user than the cost of upgrading. (This is of course debatable.)
For some users this will be a clear win, for others a lose, but MS is not doing anything to prevent *sophisticated* users from using old hardware. And presumably sophisticated users can figure out for themselves if the security improvement is worth paying for.