Well, given these dice are aimed at D&D players, you'd be surprised to hear there is only one D20.
Let me see, sit down with five players and one DM. What's the one die they all want? D20.
There's only one here. Hmm. Could Do Better.
The D4 is a mutant! Kill the mutant! One of the defining moments in a gamer's life is when they learn how to read a D4, by putting the numbers squeezed near the point rather than at the base this dice set has ruined one of those eclectic moments of clarity that all should be allowed to experience.
On the bright side, the D10 marked as 00,10,20,30 etc. is very good; it saves the eternal "but I always use yellow/green/whichever-coloured-dice-rolled-highest as the tens" argument from the unpluckly player and for me was probably worth the purchase price alone.