It looks like you have a nice, large display! While that is becoming more common, there are still many smaller displays in ParaView’s user base. We need to leave some space for visualization, hence the desire to minimize icon size.
We are moving icons from PNGs to SVGs, so at some stage we may be able to provide a setting to increase font size, much like we provide a setting to control the font size in the UI. But as with all things, that takes time. Thanks for your patience.