I was wondering why most E27 base LED lamps kept the traditional shape of incandescent lamp? Wouldn't like tubular shape use less material in production and on the otherhand in most fixture it would not matter what shape the lamp has unless it's too bog.

This is the shape people used to see the lamp.

Yup. Many fixtures are made with exposed lamps, so changing the lamp shape radically changes appereance. It's one of the reasons why people didn't really like CFLs.

This is even more true with so-called "LED filaments" lamps. Much of the manufacturing process of classic incandescent lamps can probably be carried over directly to that kind of LED lamp, notably the glasswork.

However in non-consumer applications the hassle or mimicking the old-school lamps is rarely justified, except maybe where it kind of happens anyway, say with LED retrofit tubes.

People were 'imprinted' by a classical pear shape for years, sure. But many led lamps can be sourced with cylindrical bulbs today, no problem.

Philips tried pretty radical design with their early remote phosphor lamps some ~15 years ago, but this line pretty much died out. Remember these?

In lighting you can not just change the shape of the light source, you need to change the fixtures also to match them, otherwise the combination as a system won't work.
And there comes the power of "set standard": The lamps got that shape century and half ago, because that was the shape to be the most performing and easiest to make at that time.
Then fixture makers incorporated that shape into their fixture designs.
More than century passes and even when the shape is not the best suited anymore for the lamp technology, all the common fixtures in use are designed for that shape, so if you want to make the lamp working there, it has to have that shape also. Even when bare lamp may perform better with a different one (e.g. the narrow tubular, flat in case of LEDs,...), the combination of such lamp with "standard" fixture would perfom way worse than the lamp that is by itself way worse.

It is not only about the lamp shape, it is also about e.g. the electrical connection: The Edison screw (and/or even the British bayonet style) are everything but a safe electrical connector design even in the "century ago perspective", but because it was such strong and difficult to change standard even then, people get used to its dangers and live with that. Don't forget the same Edison screw was working as a standard connector not only for light bulbs, but also as a generic electrical socket, for fuses (there it lasted way into the 20'th century), but because there was not such tight tie to match the other equipment (what connector is on a power cord does not influences nearly anything, you just need to have matching equipment cords), its use for that died quite long time ago (late 19'th century for electrical sockets, mid 20'th century for fuses,...).

GE tried to do precisely that in 2015 with the launch of its Bright-Stik LED retrofits.  They used a slim tubular envelope instead of the traditional pear shape.  See press release at https://www.businesswire.com/news/home/20150603005905/en/GE-Disrupts-Lighting-Industry-Introduces-CFL-Replacement-LED-Light-Bulb

It was a spectacular flop.  Consumers hated the appearance almlst as much as they disliked the CFL.  Glare also became a lot higher due to the smaller lighted surface.  Moreover, manufacturing costs were significantly higher because this non-standard shape never achieved the same economies of scale as the pear shaped versions - whose raw materials were made in orders of magnitude greater volumes.  The assembly of pear-shape LED lamps in Chinese factories is virtually 100% mevhanised, using machines built to handle the standard shape lamps.  The tubular versions would require machine changes that are not difficult, but would require extra effort and whose cost can never be recovered due to the smaller production volumes.

Moreover now that most retrofit lamp designs have shifted to gas-cooled filament designs, a tubular bulb would be a major disadvantage because there is less volume of gas for cooling.  Tubular bulbs are also far more expensive to process on the bulb sealing machines because they require more complex tooling to clamp the parallel-sided glass, whereas pear-shaped bulbs automatically self-centre and align themselves in conically-shaped bulb cradles that rely only on gravity for their efficient handling.

In conclusion I am not sure there would be any real advantages to engineer a tubular lamp - only a lot of disadvantages.

That's really interesting. I remember seeing some tubular E27 led lamps, I think Osram branded, but all I have havebbeen marketed for professional use more than consumer, even the ones that are not meant for replacing hid lamps.