I am of a couple minds on the subject, which is why I haven't replied before now, so it's a mistake to assume that silence means complete agreement.
A game which the same stuff and only the same stuff available on each playthrough would be too repetitive. The game does indeed need some randomness in what things you can find. But does that mean that DOS 2's system of frequent turnover is ideal? It doesn't feel ideal. I think the actual issue is getting confused.
There are two factors at play. The first is the game has a finite number of encounters (and containers) available per level which allow drops. The second is the high rate of growth in enemy HP and armor per level requiring you to turn equipment over every 1-2 levels for weapons and every 1-4 levels for armor.
I think the real issue with DOS 2's itemization is not that you need to replace items often, it's that the WAY you replace items is repetitive, time-consuming, and tedious: You are not likely to have all your gear needs for 2-4 characters with 10-11 slots each met just with what you can find from enemy drops or in containers. The rest you need to buy in stores. So you need to visit most of the available merchants, compare what they offer to your current characters loadouts, then go to the next merchant and repeat until determining what to buy.
One of the ideas behind random loot is to make it more exciting because you are hoping that the next "wow this is a cool item" item could appear at any time. Having to stop adventuring to make the rounds of the merchants blunts the wow factor. The same anticipation that the next cool item could be there at any time means you usually don't want to impulsively buy the first thing that catches your eye. So you need to keep track or remember what items looked good in what stores, then after your rounds, you buy everything which was the best improvement.
(I'm sure Qiox will try and say something along the lines of "you don't need to do that EVERY time you level up, you can keep low level gear for ages", but Qiox doesn't see game difficulty in the same way we mere non-omnipotent mortals do.)