I have two small Kubotas with loaders and no power steering. Even with all the work ive done with them, i haven't spent too much time thinking about converting them to power steering because at the end of the day, it's just.. not that bad!
BUT, there are a bunch of contributing factors. First thing is weight hanging behind the rear axle transfers weight OFF the front axle. One of my Kubotas has a backhoe on it and that tractor is much easier to steer than my other one, on which i mostly use a ~450lb box blade as counterweight. Pound for pound, the further behind the rear axle it is, the more difference it will make in steering effort improvement. So for example, tire fill will not change steering effort noticeably, but putting the same amount of weight on the 3pt will show some improvement.
Another thing is front tire/wheel details. When you don't have power steering, changes to front tires or wheels can make a huge difference in steering effort. It mostly has to do with tire scrub and scrub radius. You can think of your tires' contact patch on the ground as a circle or oval. Ideally you would like that circle to be somewhat near the point where the imaginary line of your steering axis touches the ground (ie if you drew a straight line through your kingin or upper and lower pivots, to the ground). The further your contact patch is outside of that point, the more the tire must roll backward and forward as it turns, which adds effort and makes the tire susceptible to everything in that area of the ground. You can imagine if your tire had to roll UP an incline or bump during its arc, that you would essentially be using the steering system to slightly jack up the entire front of the tractor (huge effort). At least if it spins mostly in place the effort will be more consistent. The other thing is how wide the tires are. Narrower is generally better for steering effort unless it is sinking into the ground. That's going to depend on ground conditions but if you are operating on fairly hard surfaces narrow will be better. Another thing is air pressure and tire stiffness. As you add a bunch of weight to the front tires they will squish down a bit and the contact patch will grow, making the 'swept' or scrubbed area larger, requiring more effort to turn the wheel. So, you should generally run your front tires at max rated pressure for loader work (many go above that but that's a separate topic). If you replace the front tires you would generally prefer a higher ply count, ply rating (not actually the same thing), higher load capacity, or higher max inflation pressure. Those traits all have a lot of overlap as to what they mean about the tire, so you go by whatever specs you can find.
Another thing to remember is this: Most loaders can push the front wheels of the tractor off the ground a little bit even when the bucket is fully curled and holding something. You usually have the option to push the front tires up, spin them effortlessly over the other direction, and put them back down. This is handy when you need to do a lot of steering in a short distance.
Power steering conversions are also possible, but they are usually pretty advanced DIY projects (a lot harder than adding hydraulic remotes, for example) unless you swap on a factory-style setup or someone makes a 'kit' for your tractor.
