You're right, it's wrong.
I think there’s a halfway house - but ultimately, whilst it’s difficult to ‘prove’, the biggest factor should be around intent and recklessness.
Intentional (should be send off as standard) - Luai example or deliberate hip drops etc; should receive the highest of bans (4 weeks plus), regardless of injury outcome.
Reckless (send off as standard) - Nathan Brown/Val Holmes type incident, where they’ve shot out of line/left their feet, should receive higher end of ban (3 to 4 weeks) as standard, am comfortable can be increased further if caused injury
Careless (potential for sin-bin dependent on severity) - eg Mo F (trying to effect a standard tackle, but hit high due to late movement of attacker) lower end of bans, again comfortable that any injury could be a mitigating factor in fine/ban outcome
The big problem is that we’ve made the whole MRC/Disciplinary process a legal beast with solicitors etc involved. As such, they bottle making a call on ‘intent’, but to anyone with any sort of knowledge of the game (and an independent view), it’s fairly obvious in most occasions.