Time passes different in Lothlorien
While the company may have appeared to have "tarried" as their time in Lothlorien wore on, an earlier draft on the topic suggests that they themselves hadn't aged.
The Coy. [Company] stays in Lórien for many days. They cannot count the time, for they do not age in that time, but outside in fact 30 days goes by.
They cannot count the time, for they themselves do not age or only very slowly. Outside in fact about 30 days passes.
The History of Middle-earth - Volume XII: The Peoples of Middle-earth, Chapter VI: Tale of Years
This may have been the same in the published Legendarium, however at the time Tolkien meddled with the idea that some form of time manipulation by Galadriel may have prevented the ageing of the lands of Lothlorien
This idea is supported by Celeborn in The Mirror of Galadriel (the chapter):
It is eight and thirty years of the world outside since you came to this land; and those years lie heavy on you. But the end is near, for good or ill. Here lay aside your burden for a while!
The Fellowship of the Ring - Book II, Chapter 7: The Mirror of Galadriel
Celeborn speaks of two very interesting things here, the first being that the years in "the world outside" seem to be different to those recorded in Lothlorien, again suggesting that time passes differently. Furthermore, he suggests that Aragorn can set his burden aside for a while, suggesting that Lothlorien seems like an ancient spa resort, where one forgets their pains and worries.
When asking about Gandalf, Legolas gives us a little more insight into the magical affects of Lothlorien
At first we were weary and danger was too close behind and afterwards we almost forgot our grief for a time, as we walked in gladness on the fair paths of Lórien.
A final point on why the company stayed so long is to replenish and recover after the loss of Gandalf.
you should have refuge in this City, until you were healed and refreshed. Now you shall rest, and we will not speak of your further road for a while.
The time spent in Lorien was beneficial to the Company and the gifts they received proving instrumental in their success.