Use of video helps cricket but not so sure for rugby

I am no expert on rugby. I went to the wrong type of school. We were actually told off if we played at lunchtime.
That has not stopped me enjoying the World Cup. The Japan win was great for the game - and Brighton - although I suspect South Africa will comfortably qualify for the knock-out stages anyway.
Like most other more casual fans I am still mystified by most of the penalties. The ref blows but it is utter guess work as to why and who against. The toughness of the players is incredible, but also borderline dangerous. The number of injuries is now so high that we are reaching 'something must be done' territory - albeit as a non-rugger bod I have no idea what.
I have though been intrigued by the impact of the TMO (Television Match Official - or use of video technology to you and me) on the rugby matches. It seems to me as a non-expert that in the case of rugby, video technology has a negative effect. Good rugby involves tries - but the TMO tends to result in apparent tries being ruled out. This is the opposite to what has happened in my sport, cricket, where video technology has led to umpires being more willing to award wickets. Ball tracking (Hawkeye) has shown that 'leg befores' (LBW's) are far more common than umpires had previously been willing to award.
This is not an argument for removing the use of technology in rugby to help the ref, sorry Sir, get things right. Rather I think the blazers may need to look at revising the number of points awarded so tries are encouraged. 7 points for a try and only 2 for a penalty anyone?
NB - and by the way I have backed Ireland to win the thing!