Not during the 80s and G.I. Joe but the show and others like it were part of the reason that broadcast rules were changed.
In 1990 the government passed the Children's Television Act. The entirety of it can be read here: http://thomas.loc.gov/cgi-bin/bdquery/z?d101:HR01677:@@@L&summ2=m&
Besides setting rules for local TV stations on how many hours of Educational children's programming they must show each week, the act also limits the amount of commercials on children's TV and the type of commercials that can be shown.
Much of this was done in response to studies such as this one
According to the abstract the study shows that young children, under ages 7-8, are not able to differentiate between the commercials persuasive intent to sell them something and the show they are watching. This is especially true in cases where the TV show is based on a toy line such as G.I. Joe, Thundercats, Rainbow Brite, etc. which had advertisements for the toy product during the show.
The FCC still enforces this rule as seen here where they fined a TV station for showing an Eggo commercial during Pokemon because the Eggos in question featured an image of Pikachu.
The article also explains the Children's Television Act in plain language.