When I was shopping for mine, I asked the very same question as my nearest dealer was only ordering the shuttle shifts. I use my tractor as well as other tractors I have worked with over the years, for a little bit of everything you described(and a few you didn't

and I personally wouldn't be without the creeper range of gears. I use 1-2 Low Low(creeper) for most of my brush busting with a 5' rotary cutter. Since the engine is running at full rated PTO RPM to power the cutter, your only control of speed is with the gears. In thick brush, and particularly on uneven terrain, going too fast can be real bad. The brush and tree stalks/trunks and stumps sometimes get where you don't want them and you can tear things up on the tractor or mower very quickly. Also hidden depressions and rises can pretty quickly turn what was an acceptable lean angle into an unacceptable one. It is good to be able to approach these things slowly and have a slow enough speed to be able to stop things before they get serious.
Your maximum traction force is applied at the slowest wheel speed. The ag tires need a little time for the tread teeth to depress into the soil, force it outward and get a bite. If you have too much wheel speed, the tires don't get a chance to bite and will spin. In creeper, when you come up against something that won't move, you can stop the tractor before the tires really start to dig in and do a lot of damage that you will have to smooth out.
Lastly, the creeper is great for fine positioning. A few weeks ago, I was confidently able to creep up and bring the Front End Loader with a new pellet stove setting in it, up to within a 1/4" of the threshold of my front door. I then shifted the stove from the FEL bucket to a dolly without lifting it. I just used it this last weekend to swap pickup beds between 2 trucks I am working on. The creeper allows that fine positioning and time to assess the situation before something goes crunch. It is also pretty handy for placing the post hole auger right on the mark.
If I was going to be doing a lot of loader work moving from pile A to pile B on level ground, or mow already cleared land, a shuttle's ease of shifting and higher reverse speed would probably be more desireable to me. For what I have to do, the creeper was the better choice for me.