Should cones, bursts, and areas of effect scale with the caster level?
I enjoy how the range of spells increases as you level up, often the range increase on short and medium range spells has made a tactical difference at high levels. I'd like to see the variable range expanded to apply to all spell effects, including 15ft cones becoming 20 and 25ft cones at higher levels.
Is this a valued feature or unnecessary complication?
It would work well with the whole spells need to be prepared at a higher spell slot for increased effect, like prepare at higher level for increased damage or increased area.
Also some spells get more powerful when more actions are spent to cast them, for example the heal spell becomes an area effect when 3 actions are spent to cast it. If you can spend 3 actions to cast a cone instead of 2 and gain extra area on the cast it might work.
Whether or not they should, I doubt they will. Given that spells now scale more versatility and power wise with the level at which they are cast than the actual level of the caster (though more experienced casters are more reliable at a spell that functions precisely the same).
Personally I'm not a fan of a spell AOE rigidly gaining increased size or range even when you're technically casting it at the same power level, so if such scaling were a thing I'd like it to be ignorable.
I don't think area OR range will increase at all in this edition for most spells regardless of the level or tier at which you cast it. Barring of course metamagic, whether that is built in to the spell as with using extra actions for Heal, or using an actual feat such as Reach Spell.
There are of course probably exceptions like teleport effects, where the main way of increasing the spell's power IS to boost the range.