The primary financial reason to buy DVC is to save on stays at Disney's Deluxe Resorts.
DVC provides some other discounts. For example, 10% off at a limited number of restaurants and shops. The biggest single discount is $150 off an Annual Pass, which is useful if you visit more than once per year. From time-to-time, Disney has offered other ticket discounts.
Perks are subject to change. In fact, the list of perks changes every year. Some get added; some eliminated. Early on (before I was a DVC member), Disney offered free theme park tickets. When the Boardwalk Villas opened, Disney offered free valet parking. These perks no longer are offered.
You need to fit a very specific profile in order for DVC to make financial sense. (I recognize that there are emotional reasons to buy DVC.)
If you are OK with staying offsite, at a Disney Moderate Resort, or at a Disney Value Resort, then DVC definitely is not for you. DVC makes sense only if you stay at Deluxe Resorts.
If you typically visit when Disney offers "free dining" or "room only" discounts, then DVC probably is not for you since you are likely to get deep discounts (30% or more) at Deluxe Resorts.
If you need to take out a large loan to pay for your DVC membership, then DVC probably is not for you. There is a limited set of circumstances where a loan makes sense; mostly if you intend to pay it off quickly. However, DVC loans typically are for 10 years, which nearly doubles the purchase price using Disney's financing.
Over the last couple of years, Disney has increased DVC prices significantly. Overall, purchase prices have gone from roughly $100/point to $160/point.
For most, I suspect a direct-from-Disney DVC purchase no longer makes financial sense.
Disney has started selling at the Polynesian Villas & Bungalows (PVB) at $160/point. This will go up to $165/point next month. At those prices, PVB is hard to justify financially.
For example, if you are able to visit WDW when they offer "room only" discounts and have to take out a large loan to pay for your membership, then I estimate that 30 years of vacations at Disney's Yacht & Beach Club will cost less than 30 years of vacations at PVB.
That's an incredibly long time to start saving money.
Unless you absolutely have to stay at the Polynesian (the Poly has some big fans), I suggest that you mix up your WDW vacations between stays at Moderate Resorts and some of the less expensive Deluxe Resorts (e.g. Wilderness Lodge & Animal Kingdom Lodge). Over the long-term, this likely will cost less than a DVC membership at Disney's current DVC prices.