To reverse such weakening is almost self-explanatory. Specfic concerns are that such ease with which people can be extradited is prone to abuse, by means of flimsy or even fabricated allegations (and the required "proof" for extradition in the circumstances is minimal to say the least). Once taken to another country, there is no guarantee that the standards of justice are as good as they are in the UK.
The Government should not allow such risk to fall on UK nationals, to whom it has a bounden duty to protect form such risk, first and foremost.