Sorcerer and warlock aren't similar.They indeed have boring subclasses, and at least one reason for that is that more interesting concepts get siloed into separate classes. But conceptually wizard (learns magical formulas) is quite distinct from sorcerer (empowered with innate magic at birth by a magical ancestor) and warlock (empowered with innate magic at some point by a magical patron,) which are basically the same thing. But the wizard could get some leftover from this merger, hopefully making it more interesting.
The problem is they both are usually designed by wizard fans.