I can see others naming competitors so it seems to be allowed. I intend no harm, mods feel free to delete this if it breaks rules. Just providing some information and opinion for those who are curious.
I am also using Simkl now. As others have mentioned there is already a Kodi addon for scrobbling and some addon developers are adding watchlist support to their addons. For me this is more than sufficient for my limited needs.
Just for reference, MDBlist has various tiers, starting at €1 to open up quite a lot of features. Simkl has various tiers, possibility for a one-time VIP fee and rewards regular usage with free Pro. These are acceptable pricing models, and very reasonable prices for the service offered. Easy to fork up such small amounts, and I already have.
On the other hand we have Trakt increasing their price to the point where it is approaching actual streaming service fees…no tiers, no regional pricing, no one-time fee, nothing new for the VIP tier, locking features behind a paywall. 
In my opinion, the price was already too high before the hike, especially for the limited usage of a particular feature (keeping a watchlist of things I plan to watch). Trakt is just a ‘nice-to-have’ service and was convenient but in no way essential. It doesn’t offer enough convenience to match the price, especially not now. Others may disagree, fair enough if they need the other features or are power users. Go ahead and enjoy.
The only way these changes make sense is if the objective is to reduce the number of users for whatever reason, which is absolutely your prerogative if so.
All users affected by this either have to pay up the exorbitant price, accept that they can only ever collect or plan to watch 100 items, or use a different service. An option to have larger lists for a small fee would obviously have worked very well, but that was not what was done here. There are more potential options of course but that option seems one of the better ones as opposed to ads for the free tier etc.
Personally, my income is not unlimited, nor is it in USD, and a large portion of it goes towards essentials; so I can honestly only afford support to those services that are of good value, reasonable price, have excellent features useful to me and/or treat their regular users well.
At the moment Trakt is none of these…