The task mechanic is very much designed to act as a montage scene from [insert favourite title here]. It's there to help decide an overall outcome over a period of time in a dramatic context. As Matt and Belgath point out, it's not there for routine, everyday occurrences, but those occurrences where there's some overwhelming importance, urgency, risk or whatever. You can handle such situations in a single roll, and indeed, statistically you might be better doing so, but the task system does introduce pressure, some higher odds of failure, and therefore dramatic tension - and that's deliberate. It's also designed to be collaborative too: a task might require a team of people pooling different skills, each on contributing one roll to the pot (indeed, this is how I often use the task system in my own games). So it can also be a collection of individual rolls from different contributors, each, perhaps, at a varying chance of success, to achieve an overall goal.
Like any skill rolls, you can also augment the skills needed for the task - with passions or other skills, thereby enhancing your base chance. The GM might decide that with the right resources, your skill grade is one or even two steps easier. Raw materials might even give you a starting point of 25 rather than 0.
The Task system is an abstraction. Like all abstractions, it has its quirks. However, context is everything and the dramatic context is key. The quirk of having a compromised overall chance of success, because you need to make 4 rolls successfully in sequence, can be a great way of building tension that leads to some great story telling developments that you simply wouldn't get by relying on a single roll from a highly skilled individual. Here's an example from my Mythic Britain campaign. Three armies commanded by the player characters had to amass on Lugh's Gorge to defeat the villainess. She'd set ambushes and called on curse spirits to hamper their progress. Each commander had to make either a Lore (Strat & Tac), Stealth or Locale roll that contributed to the overall outcome of their combined forces' success to reach the battle ground. I think they succeeded in either two or three of the four rolls. Their armies got there, but they were weary, sick and had sustained some light casualties from skirmishes and ambush attacks along the way. Now, a single roll could've been used as the abstraction and it would most likely have succeeded too. As GM, I could always rule that the armies were still weary and ill, but it's harder to justify, and the task process actually allowed each player to participate, to understand the stakes, and for me to narrate the effects based on each roll, as the task progressed.
In short, the math outlined in earlier posts is correct - and yes, there are quirks (and we knew about them; it was raised in playtest, if memory serves) - but we don't consider the system to be broken, because it's there to represent those occasions where the heroes are placed under prolonged stress with heightened stakes. Indeed, that quirkiness is something I consider a feature, not a bug.
A somewhat convoluted answer, but hopefully it illustrates our way of thinking. One thing that's already been suggested - by all means adjust the points required, the number of rolls needed, or the skill grade the task operates at, if that seems like the right and appropriate thing to do within the context of both the task and story. And as ever, don't forget Luck Points - if this is a team endeavour, then you may also have Group Luck points too...