watasitati ni totte, nebukuro no negokoti ha taisetu da.

にとって means something like for, to, or from the point of view of.

So 私たちにとって means:

• for us
• to us
• from our perspective

In this sentence, it sets the standard or viewpoint: the speaker is saying that, for us, the comfort of a sleeping bag is important.

A useful way to think about it is:

• A にとって B は大切だ = B is important to A

Examples:

• 子どもにとって遊びは大切だ。
  Play is important for children.
• 私にとって日本語は難しい。
  Japanese is difficult for me.

Because にとって needs a noun before it to show whose perspective we are talking about.

• 私たち = we / us
• 私たちにとって = for us / from our point of view

If you said only 私たち, the relationship would be incomplete. The sentence specifically wants to say important to us, not just mention we.

So:

• 私たちにとって = correct for expressing viewpoint
• 私たち alone = not enough for this meaning

寝袋の寝心地 is a noun phrase connected by の.

Breakdown:

• 寝袋 = sleeping bag
• 寝心地 = sleeping comfort, how something feels when you sleep on/in it
• 寝袋の寝心地 = the sleeping bag’s comfort / the comfort of a sleeping bag

The two 寝 characters are there because the words are different:

• 寝袋 literally comes from sleep + bag
• 寝心地 literally comes from sleep + feeling/comfort

So the phrase is not repetitive in a bad way; it is just combining two related words.

The particle の links them like of in English:

• X の Y = Y of X / X’s Y

So here:

• 寝袋の寝心地 = the comfort of the sleeping bag

寝心地 refers to how comfortable something feels to sleep in, on, or under.

It is made from:

• 寝る = to sleep
• 心地 = feeling, sensation, comfort

So 寝心地 is not just general comfort. It specifically means sleeping comfort.

For example, you can talk about:

• ベッドの寝心地 = the comfort of a bed
• 布団の寝心地 = the comfort of a futon
• 寝袋の寝心地 = the comfort of a sleeping bag

It often describes the quality of the sleeping experience, not just whether something is soft.

は marks the topic. Here, the sentence is talking about as for the comfort of sleeping bags, it is important to us.

So the structure is:

• 私たちにとって = for us
• 寝袋の寝心地は = as for the comfort of sleeping bags
• 大切だ = is important

Using は gives a general statement or judgment about that topic.

If you used が, the nuance could feel more like identifying or emphasizing the subject:

• 寝袋の寝心地が大切だ = It is the comfort of the sleeping bag that is important

That is not impossible, but は is more natural for a broad statement like this.

大切 is a na-adjective.

Na-adjectives behave differently from i-adjectives. In plain present tense, they need だ when they are at the end of a sentence.

So:

• 大切だ = is important
• 静かだ = is quiet
• 便利だ = is convenient

In polite speech, だ becomes です:

• 大切です

So this sentence is in plain style:

• 寝袋の寝心地は大切だ。

A native English speaker may expect something more verb-like, but in Japanese this is a normal predicate pattern.

Yes.

• 私たちにとって、寝袋の寝心地は大切だ。 = plain style
• 私たちにとって、寝袋の寝心地は大切です。 = polite style

The meaning stays basically the same. The difference is just tone:

• だ sounds plain, direct, and less formal
• です sounds polite and more neutral in conversation

If you are speaking to someone you do not know well, です is usually safer.

A helpful breakdown is:

• 私たちにとって = for us
• 寝袋の寝心地は = the comfort of sleeping bags
• 大切だ = is important

So the overall structure is:

• [viewpoint] + [topic] + [comment]

Japanese often puts context first and the main judgment at the end.

A very literal order would be:

• For us, as for the sleeping bag’s comfort, important is

Of course, that sounds unnatural in English, but it shows how Japanese builds the sentence.

The comma is mainly there to mark a pause and make the sentence easier to read.

It separates the viewpoint phrase:

• 私たちにとって、 = as for us / for us,

from the main topic and statement:

• 寝袋の寝心地は大切だ。

Japanese commas are often more flexible than English commas. This comma is helpful, but the sentence could also be written without it:

• 私たちにとって寝袋の寝心地は大切だ。

Both are correct.

Yes, very often it could be omitted if the context already makes it clear.

For example:

• 寝袋の寝心地は大切だ。

This would simply mean The comfort of a sleeping bag is important or Sleeping bag comfort matters.

Japanese often leaves out subjects or viewpoint expressions when they are understood from context. But in your sentence, 私たちにとって is included to make it explicit that this is important to us specifically.

So including it adds perspective and emphasis.

It can be understood either way depending on context, but in a sentence like this it often sounds fairly general.

Japanese nouns usually do not mark singular vs. plural clearly the way English does. So:

• 寝袋 can mean a sleeping bag or sleeping bags
• 寝袋の寝心地 can mean the comfort of a sleeping bag or sleeping-bag comfort

If this appeared in a general discussion, product review, or advice context, it would probably be understood as a general statement about sleeping bags.

If the speaker had a specific sleeping bag in mind, the context would make that clear.

Yes. A few natural alternatives are:

• 私たちには、寝袋の寝心地が大切だ。
• 私たちにとっては、寝袋の寝心地が大切だ。
• 寝袋の寝心地は私たちにとって大切だ。

These all express a similar idea, though the emphasis shifts slightly.

For example:

• 私たちにとっては adds a little contrast, like for us, at least
• moving 私たちにとって later can make the sentence flow differently

The original sentence is very natural and straightforward.