why doesn't it possible to login for making a pledge? as you give the possibility to make a rec

If I make a recurrent pledge on a cause with rewards I would appreciate of having the possibility to change the parameters of the pledge as the schedule, the amount and the stop date. And, as it appears on a cause with rewards, I also would like to know what is my reward.

The text above would be written by an end user, but i wrote it.

There is a contradiction in giving the possibility to do a cause with recurrent and rewarded pledges and do not give to the donator the possibility to manage his account.