Dutch Dominated Germany

[Homer]

My question originally was if the dutch could come to be the strongest force in a united germany.

I think they could.

Maybe I need to do more research about european history, but it just doesn't make sense to me that france could unify under a monarch while the HRE manages to plod along for so long.

France had no western neighbour, and its southern neighbours were busy with the Arabs until about 1500. Then France got problems with Spain, too, but it was already united.
France had a hundred years war with its northern neighbour, at the same time the German emperors were busy with Italians, Popes and German competitors.
In the end, Germany would have A LOT MORE enemies then France had: Popes, Poles, Slavs, Danish, Hungarians, Italians, French, English, Byzantines. And opposing German princes. The French king had Germans, English, and French nobles. That's it until about 1500. Quite a difference.

As far as warlike, the germanic tribes were known for their ferocity and they did topple to Roman Empire, the strongest entity in europe at that time. I am aware that the empire was in a mortal decline, but it seems like everytime the germanic peoples had to accomplish something, they resorted to violence.

The Roman Empire fell mainly because of inner problems and a little help of Eastern Germanic tribes - these are not the ancestors of modern Germans. These assimilated to the populations of France, Spain, Italy and Northern Africa.

One thing that bothers me though, is how germany became the battleground of europe throughout the 1400-20th century, generally because of this disunity.

the main reason is geography: Germany is the centre of Europe.

It has never made sense to me why some strong king was never able to form a kingdom rather than a patchwork of various regions with their own rulers.

1. title of emperor
2. Pope
3. Feudalism
4. foreign interest
5. short-living dynasties
But you'll probably find a lot of discussion about this in the forum. And in Literature.

I personally think that a strong germany would be able to prevent and at least end quickly most of the petty wars in europes history.

Petty wars in europes history?
Well, there were many petty wars in european history. But I'd say there were more then enough major wars!

I may be wrong in my opinion, but without germany having to prove itself in the 20th century and pissing off most of the powerful nations, we may never have had the world wars. However, TL may have been even more bloody, but somehow I doubt it.

If Germany would not have to prove itself in the 20th century, then probably most of its neighbours would love to "piss off" the Germans...