While I agree with people that Del Sol Valley is too small, should point out that if you use all the worlds, and populate every residential lot with a household, you may very well already go over the recommended sim limit for the game...so they aren't wrong regarding performance concerns.
In my game I have 2 or more of every kind of public lot across all the worlds. I have 6 restaurants, 6 parks, 5 night clubs, 4 lounges, 4 cafes, 3 bars, 3 gyms, and 2 of each of the other types. On all the remaining lots are houses with families. Just the housed sims is over 200, which is the highest the game recommends...it's at 384 counting un-housed sims, and that doesn't count the ones the game creates that are not tracked in the households menu.
I get that many of you have probably told the game to use an "unlimited" number rather than whatever is recommended (I know I have), but the dev team has to think it terms of what is recommended.
Like I said, I actually agree they should have put more lots in Del Sol Valley, I personally want to set more commercial lots in that world. But being dismissive of the reason they have given for why from the same community that also complained for years about culling is pretty silly. We, as a community, seem to want to have our cake and eat it too....things don't work that way when it comes to game performance.