IS THERE some mystical, transforming moment in the life of a sports stadium when it ceases to be obsolete and becomes instead charming and irreplaceable? That seems to have happened with places such as Fenway Park and Wrigley Field -- stadiums that are undersized, outmoded and thoroughly delightful.

If there is such a point, we hope Washington's Robert F. Kennedy Stadium will be around long enough to reach it. It started out as an austere, governmental-looking structure, but over a quarter of a century it has acquired some touches of commercial color and enough sports memories to make it a familiar, friendly place for one of the Washington area's favorite activities: the staging of Redskins' games. Moreover, it's centrally located, is convenient to the subway and has a grand setting. As Tony Kornheiser noted in a column in the Sports section recently, "There's nothing quite as stirring in Monday Night Football as that stately shot of the Capitol and the Washington and Lincoln monuments silhouetted in the background of RFK."

But RFK seats only about 55,000 people, not a large number by National Football League standards and not enough, according to Redskins owner Jack Kent Cooke, for him to make a profit on the team. So Mr. Cooke has been talking about his vision of a new, 75,000-seat, domed stadium, which could be built either in the District or in the Maryland or Virginia suburbs. Mr. Cooke, whose financial resources are considerable, hasn't proposed to finance the stadium himself (a cost of $200 million is frequently mentioned -- quite a price for a net gain of 20,000 seats), but even if he did, the project would undoubtedly require a sizable subsidy -- possibly in the form of free land or a break on taxes.

"Sadly, I think we here in Washington seem content to dawdle as time goes by," Mr. Cooke said in a speech a couple of weeks ago. "Perhaps we're guilty of cementing ourselves in the past. . . . Isn't it ironic that the governor of Maryland labors mightily to produce a stadium for a nonexistent football club?"

Gov. William Donald Schaefer has indeed just gotten a favorable court decision that allows the state of Maryland to move forward with plans for two stadiums in Baltimore. But there is a great deal of faith and hope involved in the financing plans for those stadiums, and a lot of public money is likely to go into them.

Those who think it's fine to subsidize high-priced stadiums generally argue that sports spur economic growth and development. But these claims are by no means undisputed, and besides, we've noticed there's been quite a bit of growth and development in places such as Fairfax County (to name one of the prospective candidates for a new stadium) without their having NFL fran-chises. In fact, the people and firms that move to a growing area may be a lot more interested in seeing tax money spent on schools, hospitals, roads, the mentally ill, prisons or water pipes than on a stadium.

If Mr. Cooke just wants to improve the Redskins' balance sheet, there are some things the city could do to help him without getting into massive subsidization. One would be to give the team a better deal on its lease; right now, the Redskins don't get any of the money from parking or refreshments, an absurdly favorable arrangement for the city given the circumstances. Another would be to explore the idea of building "skyboxes" in the stadium -- enclosed luxury suites to be sold to the big spenders. There's also something Mr. Cooke, as a businessman, can do, and that's raise the price of his product. Redskins' season tickets now average $20 a game, a bargain price for the hottest ticket in town. To get an idea of their real value, you might check the classified ads or the length of that season-ticket waiting list -- some 20,000 names long at last count.