The CPI does normalize. There's a hedonic adjustment model which takes into account everything from TV screen sizes and types to sleeve lengths. https://www.bls.gov/cpi/quality-adjustment/questions-and-ans...

It isn't perfect - arguably there is no such thing as a perfect way of capturing the differences between changes in what's available and what's expected over time with respect to things like CRT vs LCD monitors - but portion sizes are relatively simple for adjustment