I still would patch the EP/SP.
A patch only changes files for its own part of the game.
Base game patch -> updates files under Program Files\EA\The Sims 3
Ambitions patch -> updates files under Program Files\EA\The Sims 3 Ambitions
and so on.
1.22.9 (Generations patch) changed largely the architecture of the files in the base game program folder. It added a whole lot of sub folders for EP and SP. Now, the super all-in-one base game patches (1.22.9 or 1.24.3 so far) bring the bug fixes for the EP/SP by changing files in those new folders. So that indeed, past 1.22.9, there is no need to patch anything in the EP/SP folders. Even if you wanted you couldn't, since no additional patch for them is released anymore.
But before this change,
not patching EP/SP meant
not bringing bug fixes to your game, because you would not change any files within the respective EP/SP program folders, and the base game patch was only for base game features.
The EP/SP patches for 1.19.44 are the last big EP/SP patches (they are all around 70-90 Mb). They change quite a lot of files within the different EP/SP program folders. On the other hands, the patches released with 1.22.9, last one available since no new ones came with 1.24.3, were all very small (around 5-6 Mb) and change only very few files in their respective folders.
I recently re-installed my game twice. First time because I had also re-installed Windows and the whole schmuck, second time because I wasn't happy with my first installation of the Sims 3. Some small bugs and annoyances that were fixed in my game prior to The-Big-Comp-Clean-Up were back. Then, I had a huge bug in my first attempt to the Rock Star challenge, and that made me very angry, enough to undergo the whole uninstall/reinstall process again, but this time... I did it my way!
(check the patch table, it's easier to visualize:
link)
My first installation, I had done this (I don't use Origin/EADM, it's always manual):
Base game: big 1.22.9 cumulative patch (then 1.24.3 when it was released)
WA: 2.17.2, so the last (small) one released
AMB: 4.10.1, id
LN: 6.5.1, id
Generations: retail
The second time, I updated my EP in 2 steps:
Base game: patch directly to 1.24.3
WA: patch to 2.14.4 (75 Mb) then to 2.17.2
AMB: patch to 4.7.4 (96 Mb) then 4.10.1
LN: patch to 6.2.4 (79 Mb) then 6.5.1
Generations: retail
The only thing I've done with the game so far is my second score file for the challenge. I hit week 7 yesterday without too any problem. It seems a lot more stable, but there are many things I haven't tested yet, due to the restrictions of the rules.
So I don't say it's THE way to reinstall, I don't have enough understanding of computers and softwares for that, it's just what I have decided for me. I feel I have all the big modifications that were last released for the EP/SP (1.19.44 level)
and the last little tweaks to update those EP/SP to the new method (1.22.9 level)
and the very last updates released so far (1.24.3 big patch).