Kings of Leon, Brighton Centre, Brighton

They're hard workers, I'll give them that. Ever since they first appeared in 2003, the Kings of Leon have toured relentlessly, criss-crossing the globe and – if you believe the stories – leaving a trail of ravished maidens and STDs in their wake. Over the course of four albums they have gradually modified their sound, moving from soulful, blues-infused ditties to expansive rock anthems perfectly equipped to fill the cavernous hangars in which they now ply their trade.

Even so, it's hard to fathom exactly how they have become a mainstream proposition, boy-band looks notwithstanding. While their original peers The Strokes, The Hives and The Vines have yielded to the ignominy of anonymity, the Kings of Leon have been quietly plotting world domination, headlining festivals and selling out arenas without fuss or fanfare. Who could have known that the hirsute holy rollers from Tennessee had such steely ambition?

One thing is immediately clear – it's not showmanship that has got them where they are today. The family Followill – Caleb, Nathan and Jared, the sibling sons of a preacher man, and cousin Matthew – come with a solemn presence that tonight renders them almost immobile for the length of their set. Singer and guitarist Caleb's stagecraft extends to occasional facial twitches and, at his most animated, the tug of an earlobe. The rest of the band similarly keep their heads down, doggedly getting on with the job in hand. Even the overhanging screens, picking out old Followill footage, can't seem to lift them out of their torpor. Is this how they really are, you wonder, or have they simply lost the joy?

Not that this matters to the baying crowd who bounce, sway and chant blissfully along with every song. Indeed, looking at the audience, which comprises equal numbers of men and women and spans at least three generations, it becomes clear what a coup the Kings of Leon have pulled off. They have, over the past five years, transformed themselves into a catch-all attraction that offers something for everyone – some Seventies classic rock here, a touch of Eighties pomp-rock there; indie pop for the youngsters and a naughty lyrical wink for the girls (where once the Followills were focused on heaven, now their thoughts are firmly centred on the crotch). It is this that has propelled them to the dizzy heights of the arena band, destined to be up there with Coldplay and Muse, and makes for an ultimately dreary show, desperately lacking the raunch and rawness of their early performances.

From the up-tempo rock of their No 1 hit "Sex on Fire" to the rousing balladry of "Revelry" and the brooding "On Call", each track is expertly constructed and soullessly executed. There's no disputing that the Kings have a sharp ear for a melody and almost every song, while not a necessarily a classic, is a potential radio-hugging, fist-pumping hit. Certainly, they inspire some impassioned sing-a-longs. But played one after the other they become strangely indistinguishable, the impact diminishing slightly with each new number. And is it my imagination or is Caleb's voice thinner than it used to be? Last time I saw the band he screeched and wailed like a cat in labour. It may be that his voice is simply suited to more intimate surroundings but this time around it is, at best, workmanlike.

When Caleb announces they are going to perform "a few songs we haven't played in a long time. You probably know them better than us", you wait in hope for the rootsy swamp-rock of their 2003 debut album Youth & Young Manhood to kick in. Instead we are treated to anodyne AOR treatments of venerable old numbers, "Molly's Chambers", "California Waiting" and "Joe's Head".

Where the Kings of Leon once channelled the sounds of the Stones, Creedance Clearwater and Johnny Thunders, their touchstones now seem to be U2 and – God help them – Simple Minds. It's a curmudgeonly critic who would begrudge the Kings of Leon their success – but you can't help but dwell on what they've given up to achieve it.

Touring to 22 December; www.kingsofleon.com