That isn't a true representation of eldritch blast. At first level with the hex spell, cast as a bonus action you can get 1d10 +1d6 damage for every encounter because you can reapply hex once casted as a bonus action. Even after taking a short rest getting you spell slot back you can still reapply hex as a bonus action. At second level you can add your charisma bonus to eldritch blast via an invocation, 1d10+1d6+3* that is an average damage of 12 every attack. That isn't chicken feed and that more than eclipses a wizard's firebolt. 5-19 damage at second level that can be used for EVERY attack all day isn't something I would call weak nor underpowered. Also hex gives disadvantage to 1 chosen ability for all its ability check rolls.
Warlocks are a narrower focus from wizards but Warlocks can get multiple abilities that are "use at will." No spell slot needed just use it at will. I haven't even talked about all the other invocations that modify and improve eldritch blast. if you think a simple reading of the cantrip Eldritch blast tells you all you need to know about eldritch blast you have more research to do on Warlocks. Warlocks can do fewer things than other casters but what they can do they do it VERY well and in many instances far more often that any other caster could dream of doing.
* this assumes a 16 CHA which isn't unreasonable a stat for a caster class.
This is my observation so far too ... Warlock is definitely more bursty and versatile, especially towards higher levels, because Eldritch Blast can easily do 9+6 at level 3.
Wizard's benefit is mostly having a larger arsenal of spells.
But these are just observations from level 1 through 4.
So I think both are great in their own way.
