USGAAP Requires Firms to Expense Immediately All Internal Expenditures for R&D

Essay

U.S.GAAP requires firms to expense immediately all internal expenditures for R&D costs.Alternatively,U.S.GAAP could require firms to capitalize and subsequently amortize all internal expenditures on R&D that have future potential.
Required:
Why have standard setters chosen not to allow the capitalization alternative? How would analysts be better served if U.S.GAAP required capitalization of R&D costs?