They are dropping on my list for that reason

If we do not receive payment in full, in good cleared funds, within seven (7) business days following the sale, we are entitled in our absolute discretion to exercise one or more of the following measures, in addition to any additional actions available to us by law: a.) to impose a late charge of one and a half percent (1.5%) per thirty (30) days of the total purchase price b.) to hold the defaulting buyer liable for the total amount due and to begin legal proceedings for its recovery together with interest, legal fees and costs to the fullest extent permitted under applicable law c.) to cancel the sale d.) to resell the property publicly or privately with such terms as we find appropriate, to resell the property at public auction without reserve, and with the purchaser liable for any deficiency, cost, including handling charges, the expenses of both sales, our commission on both sales at our regular rate, all other charges due hereunder and incidental damages

Instead, by playing Grim Return, you get a chance to cast it during the end step, avoiding some of the pitfalls of casting it too soon
Card Rating List Mist Valley Shaman "Mist Valley Shaman" Rating Score by Update Information - NEW - 07/17 00:39 Review Paleozoic CambrorasterCategory exclusive link 2 monsters
For example, its been built into Lost Zone decks (pre-rotation) to give us another archetype in the meta