Why was the Holy Roman Empire/Germany unable to evolve from decentralized feudalism (and in fact became even more fractured with time) while England, France, and Poland became centralized states?

Not entirely sure if this is a proper way to respond, but the FAQ section has some decent starting points for answers, with the posts themselves listing sources a bit further down.

https://www.reddit.com/r/AskHistorians/wiki/faq/europe#wiki_the_holy_roman_empire

Specifically:

https://www.reddit.com/r/AskHistorians/comments/2ayc9q/why_did_the_holy_roman_empire_become_a/

https://www.reddit.com/r/AskHistorians/comments/1o2m99/why_did_france_west_francia_end_up_more_unified/

https://www.reddit.com/r/AskHistorians/comments/1upyg4/why_did_the_holy_roman_empire_end_up_so/

https://www.reddit.com/r/AskHistorians/comments/1hxqjs/why_did_the_french_kingdom_become_much_more/

Hope this is useful, but I'm sure an actual expert will be along shortly. I'm just a lurker that got sucked into reading the FAQ one day.