Back when it was in vogue to respond to the haka with Waltzing Matilda, I remember someone pointing out the absurdity of responding to what is effectively a death threat with a song that says "Not if we kill ourselves first".
Having said that, I always like it when home fans sing before/during a game, whether it's Waltzing Matilda, Swing Low Sweet Chariot, Bread of Heaven, whatever. It gets people pumped and tends to lead to a good game. That kind of stuff is a large part of what's fun about Premier League football.
So, the Haka isn't a death threat. Having heard the story of the Haka from a Maori, I think it's a strange one to use as a motivation for a rugby game.
The best way to neutralise any feeling if intimidation from the Haka is to understand its origin and know what it's actually saying.
Essentially, its about a Maori warrior who is running away from an enemy war party and seeks refuge with another tribe he stumbles across. This tribe's chief hides him in a food pit with his wife sitting at the entrance to protect him. The theory being that the smell of food and the woman's scent will cloak his presence from the war party's 'spirit man' who would otherwise have detected his presence with the tribe. When the war tribe leaves empty handed, he emerges and makes up a 'song of thanks' and celebrating the fact that, as a criminal fugitive, he has emerged from a dark hiding hole where he was cowering, covered in smelly food using a woman for protection, and now lives to see the sun again. And the actual lyrics focus on the fact that he had hairy masculine legs. Weird.
How is that a tough song or helpful motivation for winning a rugby match?
If you don't believe me, here's the actual story from a NZ cultural website:
"Ka mate, Ka mate - the original All Black haka - was composed in the early 19th century by famous Māori warrior chief Te Rauparaha, of the Ngāti Toa Rangatira tribe.
"Te Rauparaha was fleeing an enemy tribe seeking retribution for a past wrong he had committed against them. As he was chased across the central plateau of the North Island, fellow chief Te Wharerangi helped him hide in a pit and then instructed his wife Te Rangikoaea to sit on the pit entrance.
"After the enemy had moved on, Te Rauparaha emerged from the pit. There, in jubilant celebration of his lucky escape and in front of Te Wharerangi and his people, he performed Ka mate, Ka mate which he had composed while deep in the pit."
Haka story:
http://media.newzealand.com/en/story-ideas/history-of-the-all-black-haka/
Leader
KA MATE! KA MATE!
We're going to die! We're going to die!
We were at war
Chorus
KA ORA, KA ORA!
We're going to live! We're going to live!
But now there is peace.
Leader
KA MATE! KA MATE!
We're going to die! We're going to die!
We thought we were all going to die
Chorus
KA ORA, KA ORA!
We're going to live! We're going to live!
but now we are safe
All together
TENEI TE TANGATA PU'RU-HURU
This is the man, so hairy
because our leader, so strong and masculine,
NA'A NEI TIKI MAI WHAKA-WHITI TE ...
who fetched, and made shine the
has unified us and brought back the sunny days of
... RA! UPANE! KA UPANE!
sun! Together! All together ... !
peace. We are all working in harmony, side by side,
A UPANE! KA UPANE!
Together! All together ... !
moving in unison like the hairs on our chief's legs
WHITI TE RA!
To sun shines!
to prolong these sunny days of peace.
HI !
Yeah!
Haka Lyrics:
http://lyrics.wikia.com/wiki/The_All_Blacks:The_Haka
Knowing all this, I tend to find the Haka anything but threatening.