Roberta may have had the talent, but the only reason her stuff got published was because she was married to the boss of the company.
Roberta's games are also consistently the weakest of all Sierra games. Sure, she had cool ideas and especially her early games revolutionized the genre, but as time went on the flaws in her design approach became more and more apparent.
Her games are the most obscure and unfriendly of all Sierra adventures. Sierra games in general have a reputation for obtuse puzzles and walking death situations that are too easy to fall into. Well, guess which Sierra games have the most of those? Yep, Roberta's.
From the infamous Ifnkovhgroghprm in KQ1 to the absolutely necessary bridle hidden behind a rock on an island you only visit once in KQ4 and can never return to again, all of Sierra's worst puzzle design was Roberta's.
But her point still stands, as Sierra had plenty of other women in their company, and much more talented ones.
Jane Jensen designed the excellent Gabriel Knight, and the best entry in the King's Quest series: KQ6.
Jacqueline Austin designed the first Laura Bow game, The Colonel's Request.
Lori Cole, together with her husband Corey, designed the Quest for Glory series.
Despite her important role in gaming history, Roberta's output just pales in comparison to the other women (and men) at Sierra.