I don't know what it means to "deserve" to go to the playoffs but I do know that there are definitely a lot of conflicting elements to this.
Does a 10--6 team that had an easier schedule "deserve" to go more than a 9--7 team (or even an 8--8 team) that faced a murderer's row of opponents? I don't think so.
Yes, there is a very strong argument to be made that it would be better if the NFL moved to a genuine "seeding" format for the playoffs. But, it's also true that Divisional rivalries are a key part of competition (and marketing) in the NFL, so the preference to Division winners won't go away anytime soon.
But, I think it goes deeper than that.
By leaving the possibility that a Division winner with an 8--8 or 7--9 record can get into the Playoffs, the League keeps the incentive for teams to battle until the end of the season and get better into December. In some cases, it removes the motivation to tank the season, which means that more teams have to be on their toes against teams with poorer records as the season goes on.
For example, Atlanta and New Orleans at 4--6 both not only have a chance to make the playoffs, but, even more importantly, will be playing games over the next six weeks that can influence the outcome in other Divisions. They will go into those games as motivated as hell, rather than playing for a low draft pick.