LOW Original Gravities....

[Special brew]

Several questions:
1. If I should not care about the starting gravity, then why does almost every recipe mention it?
2. Several people said here that taking OG reading makes sense only for all-grain brewing or when trying to exactly reproduce another batch. But still what is the point of taking this reading when the boiling is over? I can't correct anything at this point, can I? If it's less then it should be, does it mean that I have to throw this batch and redo it again (using other/better ingredients)?
3. I read the reasons of OG being less then it should be. But what about the effects it has on the resulting beer? Here I am - let's say the OG reading is .010 less the in the recipe. What should I expect to see/taste from the rest of the brewing process? Longer fermentation? Color change? Taste change?..
Thank you!

Hi, if you read back through the posts you will get a good idea of why and how homebrewers use their hydrometers...and it seems to be a personal thing!
However, the hydrometer readings can help with many things:
As 'ryser2k says it can help estimate %abv. By using the OG and the FG it is possible to estimate the %abv.
As 'tnlandsailor' says it can help when creating recipes.
But as 'myndphaser' quite rightly points out, brewing is a craft not a science. And as Janx says, if you'll drink almost everything you brew... what's so important?

If you are faithfully reproducing a recipe, there seems little point in using a hydrometer... but if things should go wrong, having taken and recorded readings could indicate where a mistake or oversight was made. For example, I always take a sample of the wort just before I pitch the yeast. Only last week, the reading was higher that usual. Puzzling over this a moment made me return to the kitchen to see the 10 litre water bottle that I should have emptied into the fomenter sitting on the side!
If I had not added the extra water no doubt the brew would have been great...very full bodied. But I'm brewing to order and need consistency. So for me it's a check tool... and a confidence booster!

That's why recipes will indicate gravity readings, to act as a guide and a confidence marker... they're not rules.
Your hypothetical situation of a wort reading less that the recipe (if not temperature affected) could indicate too much water or too little malt/sugar etc. But don't ditch the brew, the resulting beer may just 'feel' as if it lacks a little 'body'. But equally you may prefer the lighter 'feel'. Or you may not be able to tell the difference.

As mentioned in previous posts, if it tastes good, does the trick and gives the buzz... is a hydrometer really that important?