Would it really?Would I use The Elizabeth line? No. Transfer through Paddington with luggage would be a nightmare
A longer trundle of your case admittedly, through a gateline (as for the HEx), and down a lift to a platform. And then level boarding (unlike the main line platforms).
Slightly more inconvenient, but hardly a nightmare.
If you had said the likelihood of getting a seat was much lower then I would agree with you, but I don’t see the transfer as a big issue.