(1) The RC Church has had some married priests in recent memory - Men who were Episcopal or Anglican priests and converted, and were allowed to take RC vows as diocesan priests. The world did not end.
(2) It is inevitable that the RC Church will one day have married priests, but they will not be priests who got married, but rather married men who became priests.
(3) The RC Church believes that the sacrament of Holy Orders is a permanent ordination, that lasts a lifetime. Thus, there are many, many men who were priests, quit, and later got married. For better or worse, they are still priests and can still administer the sacraments, though without the Church's "blessing."
(4) The biggest impediment to allowing married priests now is inertia. Where and how would they live? What about their wives and kids? Could they have outside "jobs" to earn their living? A lot of practical issues. Also, the men who are currently priests who consider that they GAVE UP a life that they would have liked may feel like they have been betrayed.
(5) Through celibacy, the Church has unintentionally and unwittingly created a life environment that is quite friendly to homosexuals and pedophiles. Although there are no hard numbers available - for obvious reasons - it is likely that the percentage of priests who are "gay" is many times the percentage in the general population - maybe 15-20%.