It’s very easy to pray for the saintly person who is in a battle yet the sinner needs our prayers as well. The sinner might have to reform their behavior to truly receive full redemption yet your prayers can help them find the light. Furthermore we have all fallen from grace and who are we to pass final judgement. Maybe just maybe by adding grace to others who appear undeserved especially in our books G-D will hear our pleas for the saintly as well. Bad things might less happen to good people if we prayer for those who appear to be damned.
FOOTNOTE- There are those who have committed such heinous acts (Mass Murders, Child rapist sorry to say etc, etc) that this post does not apply.