Why did Protestants abandon Liturgy of the Hours? In Divine office or Liturgy of the Hours as it is practiced in Catholic Church there's nothing bad for Protestants (or at least nothing of which I know that Protestants consider bad); prayer is good for all Christians and Psalms are a good basis. However, most Protestants don't pray this way. Why?

Did any of the reformers condemn it? Or did this tradition just fade away over time?

EDIT: I'm adding history, because I'm interrested mostly in the time when Liturgy of Hours vanished from practice of most Protestants (16th or 17th century? I don't know exactly). Modern Protestants' point of view has some value, but the best answer shouldn't rely on practice/ doctrine nowadays. I know that some denominations practice it (especially Lutherans); these are excluded from "protestantism" for this question's sake.

I imagine citation of some reformer, founder of some denomination, or at least a notable convert who prayed Liturgy of Hours before (i.e. former Catholic priest) or at least knew the practice and wrote anything about it. I'm not sure whether such a source is even available.

Less direct citations + few words on context and how it applies to Liturgy of Hours are also OK. For example some of early criticisms against prayer in someone other's words, including words of Bible, by someone who influenced some of the major branches of Protestantism. Such a criticism could apply if it sounds plausible to audience accustomed to Liturgy of Hours, though not necessarily understanding its significance - so "vain repetitions" as Narnian suggested are based on ignorance of the prayer's structure and therefore not acceptable to anyone knowing it, but fear of praying "only at set times" as LCIII mentioned could be easily accepted by someone who prayed it regularly for a long time, but didn't discover its value as a backbone of constant prayer.

An answer based solely on reasoning and Bible citations can be (temporarily) accepted as well if at least some of its points likely played role in the beginning of Protestantism. However, if some answer with solid historical reasoning and/or citations appears later, I will definitely accept the new one instead.
Protestantism is so broad that you can't avoid getting a broad answer. As the protestant church has no official head there is no official answer and there was never an official LOTH rejection meeting. Furthermore, some Protestant denominations still do practice LOTH. The best you can do in this case is summarize the most common Protestant beliefs and come up with the most probable yet not all-encompassing conclusions.

Here's a list with (I think) the most probable reasons to the least probable.

Protestants are more than likely not going to follow Liturgy of The Hours because...


...there are prayers to the saints/dead, which Protestants believe isn't good, so they'll throw whole Liturgy out--baby and bath water.
...it makes the prayer seem insincere, as opposed to a sincere, unscripted, heart-felt prayer conversation with God. The Protestant would cite this verse as their reasoning:


  Psalm 62:8 ESV Trust in him at all times, O people; pour out your heart before him; God is a refuge for us.

...setting a required time to pray gives the impression that that is the only or best time one needs to pray, when prayers should be constant. The Protestant would cite these verses as their reasoning:


  1 Thessalonians 5:17 ESV ...pray without ceasing.
  
  1 Thessalonians 1:2 ESV We give thanks to God always for all of you, constantly mentioning you in our prayers,
  
  2 Timothy 1:3 ESV I thank God whom I serve, as did my ancestors, with a clear conscience, as I remember you constantly in my prayers night and day.

...it's Catholic, and Protestants tend to buck against anything that Catholics promote.
...it's not in the Bible. Protestants are all about accepting no doctrine except that which is explicitly stated in the scriptures.
...it's unnecessary. While more open-minded Protestants may consider the Liturgy of the Hours helpful in its structure (ignoring prayers to the saints/dead), many would categorize it as just another reading/prayer plan similar to ones you could buy at a Christian bookstore. They give it no added spiritual significance.