They were NOT struck down for holding back part of the price of their land! Peter told them it was theirs to dop with as they would. They were struck down for seeking recognition for something they had not done.
Matt 6:2-6
2 Therefore when thou doest thine alms, do not sound a trumpet before thee, as the hypocrites do in the synagogues and in the streets, that they may have glory of men. Verily I say unto you, They have their reward.
3 But when thou doest alms, let not thy left hand know what thy right hand doeth:
4 That thine alms may be in secret: and thy Father which seeth in secret himself shall reward thee openly.
5 And when thou prayest, thou shalt not be as the hypocrites are: for they love to pray standing in the synagogues and in the corners of the streets, that they may be seen of men. Verily I say unto you, They have their reward.
6 But thou, when thou prayest, enter into thy closet, and when thou hast shut thy door, pray to thy Father which is in secret; and thy Father which seeth in secret shall reward thee openly.
KJV
tells us that we should not seek recognition at all. To seek recognition under false pretenses posed a real danger to the early church. A statement had to be made that God, while indeed gracious, is not someone to be mocked or trifled with.
Now that the church is established; it is no longer necessary to deal with such things as immediately.