Damn it. I wrote a whole long post and accidentally closed the window so I lost the whole thing *sigh*
I'll summarize.
About Fusion titlesI think a lot of the disconnect we're having here is that you don't really have experience compositing. As you said, you're a beginner. You also said you don't have experience in other compositing software yet your framing it as if Fusion is uniquely complicated compared to other compositing software. You don't have that frame of reference.
Compositing
is complicated.
When you're complaining that Fusion titles are 20 nodes and you have to dig through them to change a key-frame, that's comparatively user friendly.
The most obvious comparison to Fusion titles I can think of is Essential Graphics in Adobe's Creative Cloud. They're motion graphics templates made in After Effects that you can drag into Premiere and modify using parameters that were set up in After Effects. If they're lacking a control for something you want to change or if there's overall something you want to change, it's not as easy as Right Click > Open in After Effects. Instead you have to open After Effects, navigate to either
C:\Users\[your user]\AppData\Roaming\Adobe\Essential Graphics
or
/Users/[your user]/Library/Application Support/Adobe/Common
then find the template you want to modify, then extract it. If it was made in an older version of AE then you'll need to allow them to make a copy of that in the update AE format. What you'll be greeted with is
Those four layers that I highlighted are precomps. Any keyframes for this would be to move the whole composition, not it's individual parts. To get to those parts, you double click one to open up that composition. Where you'll see this.
Maybe you want to move part of the shield so it hides a specific part of the background. Well now you can't see that background. Unfortunately, you can't. All you can do is open them up side by side, like this so you can go back and forth between them to compare.
Then you need to add that whatever parameter you want to add in the Essential Graphics panel, save it as an Essential Graphic and then bring it into Premiere Pro again. I would say that what you had to go through to manual change some key frames was probably pretty simple compare to that whole process.
Now to be fair to Essential Graphics, they have exactly what you want. They have sliders for ease-in, ease-out, and animation speed. Something like that can be added to Fusion but that doesn't mean Fusion, as a whole, is too complicated for what it was designed for. It just means that the way people interface with Fusion titles could be a little better. It's an interchangeability problem.
About the Object Removal issue.First off, there is no motion graphics/compositing equivalent to LUTs.
Secondly, your reason for going into Fusion was because the Object Removal tool in the Color page didn't work for you. Because the Color page doesn't have any features that would allow you to do something like without having a node specifically designed to do that, you went into the Fusion page because it can do more. When it didn't have a built-in object removal node, you complained that it's too difficult and should work like the Color page which has an Object Removal tool that didn't work for you.
See the problem there? You're claiming that Fusion is flawed and difficult because it doesn't work more like the Color page which couldn't do what you wanted. You really just want that one node in the Color page to work better.
About my experience in After EffectsMy point I was trying to make was that my experience to After Effects didn't matter. After Effects isn't node-based, it's layer-based. The most I had every done in After Effects was essentially a title with maybe seven layers with most of them being assets made in Photoshop. What I did in Fusion was miles ahead of the most complicated thing I ever made in After Effects. The reason for this is that I found Fusion to way more straight forward and manageable than I ever found AE to be.
As it relates to the plug-in discussion, one of things people like about After Effects is the amount of plug-ins made for it. I don't think many people would disagree that it's more reliant on plug-ins than things like Nuke or Fusion. I remember there was a while were it was difficult for me to find After Effects tutorials where they didn't suggest buying a plug-in and many even had purchasing a plug-in as a prerequisite.
About the rain plug-in exampleI should have just said "What if you looked for rain plug-in and one didn't exist?" You wouldn't have the option to use a plug-in. You'd have to just learn to use the program or not have rain.
Even if Fusion did add a simple option to make rain, they wouldn't do it as it's own node anyway. They would make it as a template just like they already did for falling leaves, snow, smoke, bubbles, etc. because it wouldn't make sense to make a specific node that just works in the same way as a 10 node tree especially when the template allows people learn how to do their own effects.