This plugin by @slightlyangrydodo does a really fantastic job in making the design more clean, while keeping the arrows! 
Best of both worlds in my opinion!
Call for Krita UI Redesign Plugin Testers - Develop / Plugins - Krita Artists (krita-artists.org)
Standard Krita:
With the Redesign pluginâs âBorderless Toolbarsâ:
