I don't think any character made with the play test materials has had insufficient choice for available cantrips, and only the druid lacks a great regular offensive spell. With the very limited number of spells available already, adding choice here is not going to effectively increase diversity of casting options for any individual caster.
There are two fundamental changes I would make, however.
1. As I have argued elsewhere on these boards, I do think that attack cantrips shouldn't use the caster ability, but should require a ranged attack roll (so +DEX rather than spell casting ability to hit). That means that not all casters will be effective with attack cantrips. For me, that makes the choice to use attack cantrips a build choice (the player has to want it and invest character resources in order to do it effectively), and not something that all casters do equally well.
2. I would have a cleric attack cantrip that required a roll to hit (rather than a save to avoid, as with Burning Hands). I think a roll to hit (again, my preference would be using DEX) is more fun for players -- it may not be so for all, but I do't see why it's excluded. Let's allow laser clerics in the game (even if only for selected domains -- again, requiring a specific build choice).
Finally, for those wanting a fire-based cantrip, there is one that exists already -- Fire Seeds for druids. It feels underwhelming, though, and I've not seen it chosen in play. I'd be interested to hear if anyone has actual experience with the spell in play.