To be fair, it's a lot for many cars too, based on emissions. The worst polluters get to pay an initial rate based on emissions which could be up to more than £2k (!), then up to £520 for the next few years for the more expensive list price vehicles. It's an attempt I suppose to make the polluter pay/ charge the wealthy more, even if it's complicated.
If your motorbike tax is too much, consider lower cc or going electric. I suspect most on here would grumble but carrying on paying £100 a year, as compared to the total cost of ownership, it's not a big wedge of money...
But agreed, some in govt have been too busy dishing out whopping contracts to their business mates whose businesses are registered offshore so they pay feck all in tax to the UK Treasury, leaving everyday Joes like us to pick up the tab...