I remember feeling disappointed and frustrated with the 2.0 layout as well. I think it was around 2.3 that the player got some UI tweaks which let you make use of screen space in similar proportions to 1.4.x.
It's been super long since I really used a local player, but IIRC later versions of Amarok 2.x let you rearrange the panes that make up the single window interface, including IIRC stacking them into tabs which is similar to the vertical, collapsible tabs on the left side of 1.4.x.
What was exciting for me about the 1.4.x player and earlier was the contextual information provided for songs— especially lyrics fetching and Wikipedia embedding. I used the lyrics fetching to learn and sing along to hundreds of songs when I was a teenager. It took decades for streaming services to catch up on lyrics display and trivia.
I also heavily utilized the collection management features and patterns, which were so excellent. Amarok was my primary tool for organizing a collection of MP3, Vorbis, and eventually Opus files that grew into the hundreds of gigabytes, on spinning rust. The metadata fetching and editing and file renaming functions were vital for me, although later I did do a lot of maintenance with Musicbrainz Picard.
The dynamic playlists in 2.x were great for parties, and I liked moodbars for showing people specific sections of songs and the cool visuals.
Anyway, to me Clementine feels like a very cluttered hodgepodge of features and menus, in a way that Amarok never did.
