This isn't a con, the details are there for you to see and judge if it is the right tent for you or not.
Agreed, 'con' is not the right word, as you say it's not deception - the specs are given for all to see.
It's the usual case of paring specs to the bone and optimizing the headline figures to attract sales, rather than making a product suitable for typical usage.
It's worth noting that even Terra Nova, who will move heaven and earth to get their headline weights down, draw the line at offering pathetic groundsheets. Theirs are always pretty tough and have good HH levels.
For ultra-marathon participants who will tolerate anything to get the weight down, the 20D floors (or even a lot lower) are generally acceptable to them
The ultrathin flys and walls have never been a problem, at least to us.