Hate is hated due to its contrast to love, not for its own merit. We hate hate because one could love, and we love love because one could hate. All our determinations of things are fundamentally based upon the valuation of others. Remove one, the others will fall in value into meaninglessness. By removing the pain, you poison the happiness.
Let us apply this to the lie. We have the truth, correlation to love, and the lie, correlation to hate. Were we to remove the lies, or the possibility to lie, we would therefore remove the appreciation to truth. Yet if we look at the appreciation of truth, it is founded in the valuation of being true. If we remove this, then there is no necessity or inclination to speak truthful or accurate information. Essentially, we would remove the need for an individual to know things, and communication would devolve into conversations conveying ideas one would not know were fundamentally based in truth or were mere conjecture. Certainly one could ask if they were founded in truth, but due to the lack of valuation of being true, this question would be of no import. Society, in essence, would crumble.
All of this happens by the removal of the ability to lie. While the initial question does indeed not concern itself over the ability to lie being good or bad, it is a necessary component. Since the ability to lie is necessary in order for society to continue functioning (good) and for truth to continue existing as a good (good), the overall contribution of the ability to lie itself is good, but that specific instances of lying are only considered bad. Lying is, in essence, a good in itself as its primary results if unadultered by specific choices are good. We cannot judge lying based on its misuses.
Since it is a good in itself, this means any proper use of it is naturally going to be good. Any misuse of it could result in either good or bad, making the act immoral if the latter - perhaps. But anything which is not considered a misuse of the lie is indeed a moral good.
We must then constitute what a misuse of the lie is. Since we have established it as a good in itself for keeping the social structure together and by attributing value to truth, we must then deem any use of the lie which goes toward dissolving society or diminishing the ultimate value of truth as a misuse and bad.
Since lying cannot separate itself from the latter, devaluing truth, that is certainly out and can never be considered empty in it's fulfillment no matter the lie told. Then the only way to determine whether a lie is immoral is if the lie itself disallows the social structures to exist. Since society exists, and will continue to exist with lies present, all such lies have not disallowed society's existence, and are therefore still; contributing to the proper use of a lie, which is by definition moral. The only lie which would not be a moral act would be the lie which disallows society to exist. However, since it would still attribute to the value of truth, it would warrant a good and bad - therefore the act is neutral.
